Drilling Of Small Diameter Holes Research Articles

ОСОБЕННОСТИ СТРУЖКООБРАЗОВАНИЯ ПРИ УЛЬТРАЗВУКОВОМ СВЕРЛЕНИИ УГЛЕПЛАСТИКОВ

The article is devoted to the description of chip formation during ultrasonic drilling of small diameter holes in structural carbon fiber. Established that generated when drilling with ultrasound chip is qualitatively different from the chip during normal drilling less compartilhamento and the presence of truncated fragments of carbon fibres, reflecting greater uniformity of the cutting process and to facilitate chip evacuation and describes the possibility of increasing the quality of processing by reducing the number of surviving unidirectional fibers.

Evaluation of the Effect of Rock Strength on Drilling Penetration Rate and Index of Rotation Energy–A Case Study

Proper knowledge of the rocks and properties of rock will allow proper selection of the bit and speed of rotation of the drill for fast penetration and reduce the cost of drilling. Since the rock fragmentation process requires the drilling of small diameter holes for the placement of explosive material, this makes the evaluation of rock properties' effect on this operation important. This study focus on evaluating the effect of rock properties and drill parameters on drill bit penetration rate, specific energy, and index of rotational energy. Two case studies mine in southwest Nigeria were considered for this study. Rock properties, penetration rate, and index rotation energy of the drill quarry machines were determined. The obtained parameters for different drilling operations were used to develop datasets for different observations. The uniaxial compressive strength, point load, and hardness values of the case study granite have an average value of 90.56-121.43 MPa, 6.8-8.54 MPa, and 45.648.01 respectively. Prediction models were developed for the prediction of the drill penetration rate, specific energy, and index of rotation energy as a function of the rock properties. The developed regression models show a very high correlation having R2 value close to unity. Hence the proposed regression models can reasonably predict drill penetration rate, specific energy, and index of rotation energy for practical purposes.

Changeable modular oil receiver for coolant supply during deep drilling of small diameter holes

Changeable modular oil receiver for coolant supply during deep drilling of small diameter holes

Electrical Discharge Drilling of Small Diameter Holes upon Ultrasonic Field Application. Part 1. Results of Technological Experiments

Various aspects of the ultrasonic field effect on the technological characteristics of the electrical discharge drilling of small-diameter holes are studied. An increase in process stability increase upon ultrasonic field application is found, and a decrease in the scattering field of machining time values is determined. The quantitative estimation of productivity improvement is performed, and the influence of various parameters on this effect is discussed. The impact of ultrasonic oscillations on dimension precision and surface roughness is exhibited. The area of the efficient application of the electrical discharge drilling technology with ultrasonics is defined more exactly.

Efficiency Estimation of Energy Introduction of a Ultrasound Field Into the Zone of Drilling of Complex Packages From Composite Materials and Titanium

The possibility of improving the quality of holes in complex packages made of composite materials and titanium alloys in the drilling operation by using the energy of ultrasonic vibrations introduced into the treatment zone is considered. The construction of complex packages and the problems arising from their processing with an axial tool are described. The rational design of the experimental setup for testing the technology of ultrasonic drilling of small-diameter holes was chosen. The unit is based on the KUKA KR 16 R2100 robotic complex. In addition to the industrial robot, it contains a spindle attached to the robot; Ultrasonic head, dynamometer and table, on which the package made of composite materials and titanium alloys is fixed. Ultrasonic oscillations with a frequency of 22 kHz can be transmitted, depending on the execution of the installation, either to the spindle or to the table with a complex package. The device allows carrying out experiments with the imposition of unmodulated, amplitude-modulated or frequency-modulated ultrasonic vibrations on the drill or on the object table with a package of composite materials.

An experimental investigation on ultra-precision instrumented smart aerostatic bearing spindle applied to high speed micro-drilling

High speed drilling of small diameter holes ranging from 0.1 to 1mm in printed circuit board (PCB) drilling industry has been largely carried out by using tungsten carbide twist drills and high speed spindles. In high speed drilling, however, the tool wear leads to increased cutting forces and results in poor hole quality as well as the hole location inaccuracy. Both hole quality and location accuracy are further considered as significant issues in drilling multilayer and heavy copper layered PCB workpieces. This paper presents the experimental development of an instrumented smart spindle, which can examine the tool wear by measuring the axial shaft displacement (known as the axial displacement) on the fly and thus applicable to real-time drilling processes. Cutting trials using the instrumented smart spindle and a Kistler dynamometer (9345A) on the customized multilayers PCB workpiece have shown a good correlation between the axial displacement and axial drilling force measurements. The axial displacement is capable of being used to detect the drilling engagement with each copper layer. Furthermore, the instrumented smart spindle can additionally be used to prevent a thrust bearing from being over-loaded and most importantly to detect tool wear in process.

Dynamical Model for the Process of Withdrawal Formation at Deep Drilling of Small Diameter Holes w ith the Increased Relative Length

Рассматривается процесс обработки глубоких отверстий малых диаметров (менее 23,0мм) с отношением длины к диаметру (относительной длиной) более 100. Основной проблемой при изготовлении таких отверстий является предотвращение брака дорогостоящих деталей по уводу и непрямолинейности оси. Ключевой операцией технологического процесса, обеспечивающей заданные величины указанных параметров глубоких отверстий, является операция глубокого сверления. Данная операция осуществляется с применением специального инструмента и оснастки с наружным подводом смазочно-охлаждающей жидкости (СОЖ) при вращении заготовки и поступательном движении инструмента. Применяемый инструмент, обладая малой продольно-поперечной и крутильной жесткостью, работает при высоких частотах вращения заготовки и давлениях СОЖ и испытывает вследствие влияния на процесс глубокого сверления различных факторов кинематическое возмущение с частотой вращения заготовки, что является основной причиной дальнейшего изменения увода по длине обработки. Процесс образования увода является динамическим, длины инструмента могут проходить резонансные значения, что приводит к нестабильности образования и изменения увода. Анализ результатов известных исследований показал, что они не учитывают особенностей образования увода при глубоком сверлении отверстий малых диаметров повышенной относительной длины. Представлены результаты теоретических исследований по разработке динамической модели процесса образования увода с учетом особенностей процесса глубокого сверления отверстий малых диаметров повышенной относительной длины, предложены рекомендации по уменьшению увода и непрямолинейности оси, включая управление уводом.

Fast drilling of small-diameter holes by core flat drills

Attention focuses on the fast drilling of small-diameter holes by core flat drills, hard-alloy drills, and unidirectional drills with the supply of working fluid to the cutting zone. Means of improving the productivity are discussed. The best approach to drilling small-diameter holes is outlined.

High-speed drilling of small-diameter holes by core flat drills

Examples are presented to illustrate the high-speed drilling of small-diameter holes (up to 10 mm) by core flat drills: holes (diameter 7 mm) in a discharge valve; and the drilling two-part holes consisting of a cylindrical section (diameter 3.8 mm) and conical section (base diameter 10 mm) in a metal housing.

Experimental Substantiation of a Method of Improving the Efficiency of Ultrasonic Drilling of Small Diameter Holes

Based on the analysis of trends in the development of aviation and rocketry and ground transportation, the prospect of use of high-alloy steels, and titanium-based alloys with high strength, heat-and corrosion-resistant properties is established. It is shown, that high strength and elasticity of mentioned alloy groups adversely affect the dynamics of cutting process and the resistance of the cutting tool. Processing of small diameter holes is especially difficult due to the small longitudinal stability of the instrument, chip evacuation problems, grooves sticking to the surface almost zero cutting speed near the core. The results from the analysis of works of domestic and foreign scientists have shown that the message sent to the drill by ultrasonic vibrations of the small amplitude reduces axial force and cutting moment due to reduced friction caused by local thermal effects and relief of dislocation motion. At the same time, it is stated that the stable results of the effectiveness of ultrasound were not received in relation to the small diameter end tools until recently because of additional dynamic loads reducing the longitudinal stability and therefore it is impossible to report the instrument optimal oscillation amplitude to facilitate cutting. The working hypothesis of increase of efficiency of the ultrasonic drilling of small diameter holes proposes to consider correlation frequency supplied to the ultrasonic instrument, structural parameters and physical and mechanical properties of the material and to drive oscillations in the plane of the main cutting edges which would significantly reduce the magnitude of the oscillation amplitude. Experimental studies on ultrasound indentation, micro cutting and drilling titanium alloys have confirmed this hypothesis. It was established that at the moment the drill receives a message with the oscillation frequency of 30 kHz when machining titanium alloys, the axial cutting forces decrease by 70 – 80 % and the tool life increases by 2.2 times.

Optimizing the high-speed drilling of small-diameter holes by core flat drills

A model is developed for optimization of the high-speed drilling of small-diameter holes by core flat drills. Thanks to the structure of the model, the problem reduces to optimization of the process under constraints associated with optimization of the bit’s structure and geometry.

Substantiation of type and parameters of downhole air hammer with a view to increase small diameter hole drilling velocity

The article substantiates the need of designing a rotary–percussion drilling tool to drill holes 40–60 mm in diameter and to 50 m long. The drilling rig with a downhole air hammer has been designed and manufactured. The authors have carried out analytical and experimental research to determine drilling velocity in different rocks of varying hardness.

Quality Improvement by Parameter Optimization in Laser Trepan Drilling of Superalloy Sheet

Drilling of small-diameter holes meeting stringent quality standards in superalloys such as Inconel718 (having widespread applications in aeroengine component manufacturing) has always been a challenging task. Laser drilling has wide applications in the aerospace industry. Laser trepan drilling (LTD) provides better control over the drilled hole geometry compared with laser percussion drilling to fulfill the higher dimensional accuracy requirement. This article presents an integrated approach of artificial neural network and genetic algorithm for the modeling and optimization of geometrical quality characteristics such as hole taper and circularity during LTD of 1.6 mm thick Inconel718 superalloy sheet. The optimum results show considerable improvements in hole taper, and hole circularities at laser beam entry and exit sides. Higher values of laser pulse frequency and trepanning speed in the present range have resulted in more circular holes with reduced taper.

Fabrication of Fine Mesh Filter Screen with Pulsed Laser

This paper proposes a novel manufacturing process of a fine mesh filter screen with a pulsed laser. The fine mesh filter screen, made of stainless steel, has many small diameter holes with high aspect ratio and fine pitch. In the conventional process, an electron beam drills in a vacuum. However, this is very costly because of the expensive equipment required and batch process. Therefore, a laser drilling process for small diameter hole drilling in air with higher flexibility was proposed. The post-processes after the laser drilling completed the fine mesh filter screen.

Establishing the electrical discharges weight in electrochemical discharge drilling

The electrochemical discharge machining (ECDM) offers an alternative to high technology equipments for drilling of small diameter holes in the case of difficult to machine materials. For a machining system based on the semidielectric liquid use and on the electric discharges initiated by contact break-out, the weight factor of the electrodes contact period is evaluated and the weight factor of the electrical discharges during this contact period is expressed. The paper presents some geometrical considerations which permit to conclude that the material removal rate depends on the characteristics of the motion and on some dimensions of the elements belonging to the crank mechanism. The influence of the input parameters on the axial electrode — tool wear and on the drilling speed is discussed.

Position Control of Drill Edge at a Small Diameter Drill

In this paper, the relationship between the cutting resistance force and the machine state was investigated regarding the drilling of small diameter holes by analyzing actual experimental data. From these results, the feasibility of controlling the machine state in terms of the position and rotation angle of the cutting edge and estimating the conditions from a control engineering viewpoint were theoretically examined. The mathematical model in this study provided an observable condition in terms of the position and rotation angle of the cutting edge using state observers.

Plasma Channel Miniature Hole Drilling Technology

With growing economic and environmental pressures, oil companies seek ways to increase the oil recovery from every well. Re-entry drilling of horizontal sidetracks from existing wells and multilateral drilling for new wells are techniques which help to achieve that increase. However, new approaches are needed to reduce the cost and to improve efficiency of rotary drilling methods used for these purposes. A new nonrotary plasma channel drilling (PCD) method for drilling of small diameter holes (3.5-15 cm) in oilfields for sidetrack creation and multilateral drilling is described in this paper. The method relies upon the use of the energy of impulse spark discharges which are formed inside the rock formation ahead of the drill position. Repeated formation of the plasma channel results in an effective and controlled drilling action. Plasma channel drills developed at Strathclyde University are able to cut clearly defined circular holes in medium hard sandstone with speeds of up to 16 cm/min using specific energies as low as 400 J/cm/sup 3/. Plasma channel drilling has the potential to increase the lifetime of oil wells and would significantly reduce the cost of exploration drilling and subsurface data acquisition. PCD technology can also be a cost-effective and practical solution for other applications such as mineral mining, water boring and scale removal where micro-hole drilling is essential.

Drilling of Small Diameter Holes for Circuit Connection of Printed Wiring Board (Hole Internal Damage and Geometoric Dimension of Fiber Bundle of GFRP)

Drilling of Small Diameter Holes for Circuit Connection of Printed Wiring Board (Hole Internal Damage and Geometoric Dimension of Fiber Bundle of GFRP)

Real-time fuzzy logic control for maximising the tool life of small-diameter drills

Drilling of small-diameter holes is an important yet difficult machining process. This, however, is commonly done on machines with hand feeding as the drill breakage is a critical and most trouble making issue in an automated manufacturing system. In most production factories, in order to reduce risk of tool breakage, cutting tools are replaced based on an average tool life and are not used as long as they can work. To tackle the problem, a simpler yet more effective method is introduced to develop a fuzzy logic controller based on the on-line diagnosis of drill conditions for automated small-diameter drilling operations. Experimental work has been conducted to obtain the process information and observe the system behaviours which are interpreted by using systematic analysis as an aid to the design of fuzzy logic controller. The methodology presented in this paper is expected to be applied to automated machining systems to improve the drilling process performance and reduction of production costs by maximising the use of drill life and preventing drill failures.

プリント基板の小径穴あけにおける曲がりに関する研究

In recent years, needs for drilling small diameter holes (φ0.2-0.4 mm) are increasing, accompanying the development of higher wiring density of printed wiring boards. However, the drilling of small diameter holes includes many technically difficult problems which must be solved. In contrast to drilling of normal diameter (φ0.5-1.2 mm) where epoxy smear, surface roughness of the hole wall, tool life, etc. are important, small diameter drilling has a different set of performance criteria : drill breakage, initial positional accuracy and hole bending. This investigation was conducted to examine hole positional accuracy and hole bending in relation with tool wear using φ0.4 mm drill to several kinds of glass epoxy circuit board. Furthermore, to limit initial slippage and then bending, vibrant drilling and drilling with a cross-thinned drill were carried out. A numerical analysis was executed to obtain accurate flexural rigidity of the drill which has an effect on the slippage before the drill point has stayed at a certain position and on hole bending even more. Conclusions are summarized as follows : (1) Amount of hole bending is generally affected by that of tool wear, but initial positional accuracy is less affected. (2) Hole bending develops with drilled depth without hole wondering (Burnhum, 1980). (3) Vibrant drilling is effective for minimizing hole bending but less for limiting initial slippage. (4) The effect of cross-thinning on hole bending is as evident as of vibrant drilling, but not on initial slippage.