• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.6
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• pp.201-206
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• 2001

The hole-drilling method makes a little hole through the metal surface that has residual stress and measures the relieved stress with a strain gage. It is used widely in measuring the residual stress of surfaces. In this method, the inclined hole is one of the source of error. This paper presents a finite element analysis of influence of the inclined hole for the uniaxial residual stress field. The stress differences between measured and applied residual stress increase proportionally to inclined angle of the hole. The correction equations which easily obtain the residual stress taking account of the inclined angle and direction are derived. The measurement error of stress due to the inclined hole can be reduced to around 1% through this study.

• Journal of Mechanical Science and Technology
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• v.15 no.12
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• pp.1647-1654
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• 2001

The hole drilling method is widely used in measuring residual stress in surfaces. In this method, the inclination of holes is one of the sources of error. This paper presents a finite element analysis of the influence of inclined holes on the uniaxial residual stress field. The error in stress has been found to increase proportionally to the correct inclined angle of the hole. The correction equations by which one may easily obtain the residual stress, taking account of the inclined angle and direction, have been derived. The error of stress due to the inclined hole has been reduced to around 1% using the correction equations.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1253-1256
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• 2005

An Experiment was carried out to study burr minimization in drilling on the inclined exit surface. Several different drills, exit surface angles and cutting conditions were selected to determine their influences on burr formation. In drilling operation, there are not only flat exit surfaces but also inclined exit surfaces which is described as inclination angle. Inclination of exit surface causes a quiet different burr formation when comparing with flat surface. Burr formation mechanisms are analyzed according to the drill geometries and cutting conditions. Several schemes for burr minimization on inclined exit surface were proposed. Burr geometry in each drill and cutting condition are measured by laser measurement system.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.9 s.186
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• pp.47-53
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• 2006

An Experiment was carried out to find the scheme far minimization of burr formation on inclined exit surface in drilling. Several drills with different geometry are used for drilling the workpiece with inclined exit surface. Step drills are specified with step angle and step size. The influence of the inclination angle of exit surface on burr formation was observed, which enables to analyze the burr formation mechanism on inclined exit surface. Along the edge on the inclined exit surface, burrs are formed by the bending deflection to feed direction and also burrs are formed in exit direction of cutting edge. To minimize the burr formed in feed direction, the corner angle which is formed by the inclination angle and step angle must be large enough not to be bent to burr. By decreasing step angle of drill and decreasing the distance between two axes of two holes, burr formation at the intersecting holes can be minimized. Burr formation mechanisms are analyzed according to the drill geometries and cutting conditions. Several schemes far burr minimization on inclined exit surface were proposed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.415-416
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• 2009

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1315-1320
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• 2008

An experimental study was carried out to study the solid-liquid mixture upward flow in a vertical and inclined annulus with rotating inner cylinder. Lift forces acting on a fluidized particle plays a central role in many importance applications, such as the removal of drill cuttings in horizontal drill holes, sand transport in fractured reservoirs, sediment transport and cleaning of particles from surfaces, etc. Field measurements have revealed that the pressure drop over a borehole during drilling of a slim oil well or a well with a long reach can depend significantly on the rotation speed of the drill pipe. An accurate prediction of the annular frictional pressure drop is therefore important for conditions where the annular clearance is small. Effect of annulus inclination and drill pipe rotation on the carrying capacity of drilling fluid, particle rising velocity, and pressure drop in the slim hole annulus have been measured for fully developed flows of water and of aqueous solutions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.773-776
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• 2005

An Experiment was carried out to study deburring in frilling hole on the Inclined exit surface. Two different deburring tools, exit surface angles, materials and cutting conditions were selected to check their performance using CNC machining center. In deburring operation, there are not only flat exit surfaces but also inclined exit surfaces which is described as inclination angle. Inclination of exit surface causes a quite different burr formation when comparing with flat surface. Deburring characteristics are analyzed according to the deburring tools and cutting conditions. Several strategies for a effective deburring on inclined exit surface were proposed.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.369-372
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• 2008

An experimental study is carried out to study two-phase vertically upward hydraulic transport of solid particles by water in a vertical and inclined (0${\sim}$60 degree) concentric annulus with rotation of the inner cylinder. Rheology of particulate suspensions in shear-thinning fluids is of importance in many applications such as particle removal from surfaces, transport of proppants in fractured reservoir and cleaning of drilling holes, and so on. Annular fluid velocities varied from 0.2 m/s to 1.5 m/s for the actual drilling operational condition. Macroscopic behavior of solid particles, averaged flow rate, and particle rising velocity are observed. Main parameters considered in this study were radius ratio, inner-pipe rotary speed, fluid flow regime, and particle injection rate. For both water and CMC solutions, the higher the concentration of the solid particles is, the larger the pressure gradients become

• Geomechanics and Engineering
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• v.38 no.2
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• pp.107-123
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• 2024

The drilling angle of the well is an important factor that can affect the sand production process and make its destructive effects more severe or weaker. This study investigated the effect of different well angles on sand production for the Asmari Formation, located in one of the oil fields southwest of Iran. For this purpose, a finite difference model was developed for three types of vertical (90°), inclined (45°), and horizontal (0°) wells with casing and perforations in the direction of minimum and maximum horizontal stresses, then coupled with fluid flow. Here, finite element meshing was used, because the geometry of the model is so complex and the implementation of finite difference meshes is impossible or very difficult for such models. Using a combined FDM-FEM model with fluid flow, the sand production process in three different modes with different flow rates for the Asmari sandstone was investigated in this study. The results of numerical models show that the intensity of sand production is directly related to the in-situ stress state of the oil field and well drilling angle. Since the stress regime in the studied oil field is normal, the highest amount of produced sand was in inclined wells (especially wells drilled in the direction of minimum horizontal stress) and the lowest amount of sand production was related to vertical wellbore. Also, the Initiation time of sand production in inclined wells was much shorter than in other wellbores.

• Interaction and multiscale mechanics
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• v.4 no.1
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• pp.1-16
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• 2011

The inverse problem about the theoretical analysis of a drill string bending in a channel of an inclined bore-hole with localized geometrical imperfections is studied. The system of ordinary differential equations is first derived based on the theory of curvilinear flexible elastic rods. One can then use these equations to investigate the quasi-static effects of the drill string bending that may occur in the process of raising, lowering and rotation of the string inside the bore-hole. The method for numerical solution of the constructed equations is described. With the proposed method, the phenomenon of the drill column movement, its contact interaction with the bore-hole surface, and the frictional seizure can be simulated for different combinations of velocities, directions of rotation and axial motion of the string. Geometrical imperfections in the shape of localized smoothed breaks of the bore-hole axis line are considered. Some numerical examples are presented to illustrate the applicability of the method proposed.