• Explosives and Blasting
• /
• v.25 no.1
• /
• pp.67-77
• /
• 2007

The drill monitoring data are useful for the detection of abrupt and unexpected changes in ground renditions. This paper introduces a new approach to how drill performance parameters can be used for the prediction of quantitative rock mass properties ahead of tunnel face and the blasting design. The drill monitoring parameters available for the predictions include the instantaneous advance speed, thrust force, torque, tool pressure and penetration rate. The assessment of the drill monitoring parameters will be able to build a database provided that in-situ drill monitoring informations are accumulated and enable us to make a reasonable blast design based on quantitative assessment of rock mass.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.1055-1058
• /
• 2002

Drilling process is one of the most common, yet complex operations among manufacturing processes. The performance of a drill is largely dependent upon drilling forces. Many researches focused on the effects of drill parameters on drilling forces. In this paper, the stresses occurring in drilling process are analyzed by finite element method. The analytic drilling forces considering the drill parameters and drilling conditions are used. Also, with ANSYS, geometric modeling and mesh generation of drill is performed automatically. From the study, optimal drill design and drilling condition determination may be achieved.

• International Journal of Fluid Machinery and Systems
• /
• v.9 no.1
• /
• pp.39-46
• /
• 2016

A high frequency hydraulic rock drill drifter with sleeve valve is developed to use on arm of excavator. In order to ensure optimal working parameters of impact system for the new hydraulic rock drill drifter controlled by sleeve valve, the performance test system is built using the arm and the hydraulic source of excavator. The evaluation indexes are gained through measurement of working pressure, supply oil flow and stress wave. The relations of working parameters to impact system performance are analyzed. The result demonstrates that the maximum impact energy of the drill drifter is 98.34J with impact frequency of 71HZ. Optimal pressure of YZ45 rock drill is 12.8 MPa-13.6MPa, in which the energy efficiency reaches above 58.6%, and feature moment of energy distribution is more than 0.650.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.6 no.4
• /
• pp.138-146
• /
• 1997

The optimal drill helix angle, point angle, and cutting conditions are recommended in the study so as to maximize the drilling performance by investigating the experimental reaults concerning with the state of chip formation, roundness of machined holes, and geometry of projected burr at hole exit, which are examined under the conditions of various helix angles, drill point angles of twist drill, cutting speeds, and feeds in operional parameters. In the easiness of chip escape, the helical type of chip is producted when a helix angle is 30$^{\circ}$, drill point angle 118$^{\circ}$, 140$^{\circ}$and feed is st between 0.1 and 0.15mm/rev. Roundness of machined hole is improved when the helix angle is 37$^{\circ}$, drill point angle is 118$^{\circ}$, and feed is 0.15mm/rev. The height of projected burr at the button of machined hole increases when the drill point angle and helix angle becomes large.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.14 no.6
• /
• pp.1523-1532
• /
• 1990

The objective of this study is to develope an optimized multi-facet drill (MFD). The principal factors that affect drilling performance are its geometry and the cutting conditions. In particular, the helix angle in the total twist angle of the twist drill, affects much morgen influence on the dynamic and static stiffness and on determining the characteristics of the chip disposal capacity of the drill. In this study, considering the helix angle as a major parameter, the model was developed. From this model, the deformation of transverse direction was simulated with the bending forces applied. The performance of a drill largely depends upon drilling forces. Comprehensive models for predicating the drilling thrust and torque are developed for the different drill geometries. The effects of MFD geometric parameters on thrust and torque are also deduced from the prediction models, from which an optimal drill geometry is found with the emphasis on minimum drilling forces.

• International Journal of Precision Engineering and Manufacturing
• /
• v.6 no.1
• /
• pp.65-72
• /
• 2005

Drilling process is one of the most common, yet complex operations among manufacturing processes. The performance of a drill is largely dependent upon drilling forces, Many researches focused on the effects of drill parameters on drilling forces. In this paper, an effective theoretical model to predict thrust and torque in drilling is presented. Also, with the predicted forces, the stress analysis of the drill tool is performed by the finite element method. The model uses the oblique cutting model for the cutting lips and the orthogonal cutting model for the chisel edge. Thrust and torque are calculated analytically without resorting to any drilling experiment, only by tool geometry, cutting conditions and material properties. The stress analysis is performed by the commercial FEM program ANSYS. The geometric modeling and the mesh generation of a twist drill are performed automatically. From the study, the effects of the variation of the geometric features of the drill and of the cutting conditions of the drilling on the drilling forces and the stress distributions in the tool are calculated analytically, which can be applicable for designing optimal drill geometry and for improving the drilling process.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2013.05a
• /
• pp.1359-1360
• /
• 2013

• Journal of Biosystems Engineering
• /
• v.22 no.4
• /
• pp.401-410
• /
• 1997

Scattering of seeds is one of the problems in the hill- dropping planters with a roller-type metering device. For crops like rice, corns and beans, the hill-dropping is own better for a high yield than the drill planting. The roller type metering device has been used for the drill planters and has many advantages. However, it has a problem of scattering of seeds when they are placed on rows. In this study a method was developed to design the roller type metering device fir the precision hill-droppings. Design parameters were derived to configure completely the geometries of the roller and brush. The method was applied to the design of the metering device of the rice seeding machines. The field test showed that the metering device designed by the method made a better performance of seed placement than that made by the precvious one. The method also can be applied to the design of metering devices for the precise hill-droppings of other crops.

• Journal of the Semiconductor & Display Technology
• /
• v.14 no.2
• /
• pp.47-52
• /
• 2015

In this paper, the performance of uncoated- and Titanium nitride aluminium TiAlN-PVD coated- carbide twist drills were investigated when drilling aluminium alloy, Al 6061. This research focuses on the optimization of drilling parameters using the Taguchi technique to obtain minimum surface roughness and thrust force. A number of drilling experiments were conducted using the L9 orthogonal array on a CNC vertical machining center. The experiments were performed on Al 6061 material l blocks using uncoated and coated HSS twist drills under dry cutting conditions. Analysis of variance(ANOVA) was employed to determine the most significant control factors. The main objective is to find the important factors and combination of factors influence the machining process to achieve low surface roughness and low cutting thrust force. From the analysis of the Taguchi method indicates that among the all-significant parameters, feed rate are more significant influence on surface roughness and cutting thrust than spindle speed.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.33 no.4
• /
• pp.290-297
• /
• 1997

Underwater robotic vehicles(URVs) are used for various work assignments such as pipe-lining, inspection, data collection, drill support, hydrography mapping, construction, maintenance and repairing of undersea equipment, etc. As the use of such vehicles increases the development of vehicles having greater autonomy becomes highly desirable. The vehicle control system is one of the most critic vehicle subsystems to increase autonomy of the vehicle. The vehicle dynamics is nonlinear and time-varying. Hydrodynamic coefficients are often difficult to accurately estimate. It was also observed by experiments that the effect of electrically powered thruster dynamics on the vehicle become significant at low speed or stationkeeping. The conventional linear controller with fixed gains based on the simplified vehicle dynamics, such as PID, may not be able to handle these properties and result in poor performance. Therefore, it is desirable to have a control system with the capability of learning and adapting to the changes in the vehicle dynamics and operating parameters and providing desired performance. This paper presents an adaptive and learning control system which estimates a new set of parameters defined as combinations of unknown bounded constants of system parameter matrices, rather than system parameters. The control system is described with the proof of stability and the effect of unmodeled thruster dynamics on a single thruster vehicle system is also investigated.