Large Hole Diameter Research Articles

LASER CUTTING OF LARGE DIAMETER HOLES INTO ALUMINUM FOAM

Laser cutting of large diameter hole in aluminum foam is carried out and morphological changes in the cutting section are examined using scanning electron microscopes, energy dispersive spectroscopy and X-ray diffraction. The thermal stress fields in the cutting section are computed in line with the experimental conditions. Finite element code is incorporated in the numerical simulations. It is found that the cut section is free from defects such as large size burrs and dross attachments. The thermal stress predicted is less than the yielding limit of the workpiece. The presence of air trapped within the pores prior to laser irradiation in the workpiece results in the formation of oxide compounds at the cut sections.

Body Join Drilling for One-Up-Assembly

Over 1,200 large diameter holes must be drilled into the sideof-body join on a Boeing commercial aircraft’s fuselage. The material stack-ups are multiple layers of primarily titanium and CFRP. Due to assembly constraints, the holes must be drilled for one-up-assembly (no disassembly for deburr). In order to improve productivity, reduce manual drilling processes and improve first-time hole quality, Boeing set out to automate the drilling process in their Side-of-Body join cell. Implementing an automated solution into existing assembly lines was complicated by the location of the target area, which is over 15 feet (4 meters) above the factory floor. The Side-of-Body Drilling machines (Figure 1) are capable of locating, drilling, measuring and fastening holes with less than 14 seconds devoted to non-drilling operations. Drilling capabilities provided for holes up to ae” in diameter through stacks over 4.5” thick in a titanium/CFRP environment. Using high precision servo control, each layer could be customized with specific drill parameters optimized to improve hole quality and decrease drill cycle time. Drill life was improved by tracking depth drilled for each drill bit. The drilling process is stabilized by rigid support structure which is optimized for both stiffness and natural frequency resulting in deflections no greater than 0.020 inches. Each drilling machine is light-weight and mobile to accommodate multiple work zones in multiple assembly lines. One-up assembly was achieved by using custom doweling/clamping fasteners automatically installed by the machine in strategic locations to provide the proper part clamping.

Numerical Investigation Based on Orthogonal Design of Structural Parameters on Large-Diameter DTH Hammer Bit

To achieve cutting transport with air reverse circulation in dry and shallow large-diameter holes of rock-socketed pile, and to solve the technical problem with airlift and pump reverse circulation, a large-diameter reverse circulation bit innovatively designed based on ejecting. Meanwhile, the orthogonal design method applied to explore the application feasibility of ejector theory in use of in air reverse circulation drilling. Through theory analysis, three key geometry parameters of air reverse circulation bit have proved to have direct affect on the function of cutting transport, including the diameter of nozzles (Dn), the number of nozzles (N), the angle of inclination (θs). The results have shown that reverse circulation effect of large-diameter bit designed based on ejecting is valid and stable. Further while the air volume of GQF-16 hammer bit goes to 90m3/min, a configuration of parameters with Dn=20mm, N=3, θs=35°are the most ideal parameter combinations.

Study of the heat transfer and flow resistance of large and small hole (LASH) baffle heat exchanger

In this study, heat transfer and flow resistance properties of large and small hole (LASH) baffle heat exchangers are studied with experimentally verified numerical models. Effects of the large hole diameters and baffle pitches are investigated. Results show that as a result of parallel flow, the shell-side pressure drops of the LASH baffle heat exchangers are greatly decreased compared with that of the conventional segmental baffle heat exchanger for the same baffle pitch. If the large hole diameter and baffle pitch are properly chosen, the LASH baffle heat exchanger presents a larger shell-side heat transfer coefficient and lower shell-side pressure drop. For the same shell-side pressure drop, the shell-side heat transfer coefficients of the LASH heat exchangers can be increased by as much as 25% compared with the conventional segmental baffle heat exchanger.

COMPARISONS OF SPRAYING STRUCTURE AND ROCK BREAKAGE CHARACTERISTICS OF ROUND STRAIGHT, SWIRLING, AND STRAIGHT-SWIRLING INTEGRATED JETS

In order to solve the incompatibility between the diameter and the depth of borehole in high-pressure jet drilling, a novel nozzle that incorporates both advantages of a round straight jet and a swirling jet was designed. The flow field structure and rock breakage characteristics were investigated in experiments for these three nozzles, which generate round straight jet, swirling jet, and straight−swirling integrated jet respectively. Meanwhile, three-dimensional flow fields were simulated for these three jets in terms of a k-ε turbulent model. The results reveal that the straight−swirling integrated jet has features of both a round straight jet and a swirling jet, inheriting both the deep penetration of a round straight jet and the large impact area of a swirling jet, but with larger hole diameter than the round straight jet and greater depth than the swirling jet. The axial velocity of the integrated jet has no potential core compared with a round straight jet, but is much higher than a swirling jet without a protrusion left at the bottom of the drilling hole. The tangential velocity of the integrated jet showing a radial M-shape distribution can form a large aperture, and the symmetrical velocity distribution presents obvious crossflow layers that are helpful for removal of rock fragments from the matrix. The numerical simulation results agree well with the actual flowing structure and the rock breakage features. A hole with expected characteristics can be drilled through adjusting nozzle structural parameters.

Guide to Borehole-Enlargement-Tool Selection

This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper SPE 142431, ’A Practical, Application-Based Guide to Borehole-Enlargement- Tool Selection,’ by J. McCarthy, SPE, J. Rebellon, SPE, S. Barton, SPE, and R. Rambhai, National Oilwell Varco, prepared for the 2011 Brazil Offshore Conference and Exhibition, Macae, Brazil, 14-17 June. The paper has not been peer reviewed. Borehole enlargement (BHE) has become commonplace. Still, it can be very demanding from planning and execution points of view, particularly in deepwater basins. To address the needs of challenging applications, a variety of tools has been developed. The two primary BHE methods use either eccentric or concentric tools. Depending on the type of well that is being drilled and the formation characteristics, the engineer must choose the optimal bottomhole assembly (BHA) and drilling parameters for successful BHE. Understanding the application is critical in delivering a successful BHE operation. Introduction BHE technology has enabled exploiting complex and unconventional reservoirs. Heavier and larger casing strings are set at greater depths, allowing operators to obtain improved recovery rates from the reservoirs. Each application must be analyzed thoroughly to provide the best design. Proper selection of BHE technology is critical. Improper selection of BHE technology can lead to complete loss of the well. For this paper, a BHE tool is one that can expand a borehole beyond the diameter at which it can pass through. Typically, this means creating a borehole larger than the inner diameter of the casing already in place. BHE tools are defined by their pass-through diameter and their expanded diameter, or drill size. BHE tools can pass through casing (or other restriction) to create a larger-diameter hole than the restriction and then can be retrieved safely from the well. To select the appropriate BHE technology, the engineer must understand the intricacies of the application and configure the drilling system to provide the best results in an economical and safe manner. Several factors affect this selection, some of which are set before the operation begins. Factors such as economics, rig capabilities, borehole quality, and drive type or system used to drill the well must be reviewed during the selection process. BHE Technology Fig. 1 shows the two primary categories of BHE tools: eccentric and concentric. Tools can be placed in the drillstring at two locations (at the bit or up in the drillstring). A third category of tools, the hole opener, often is thought of as a BHE tool, but these tools cannot generate a borehole larger than the minimum restriction of a well, so they do not fit the definition used here. However, they are sometimes used in conjunction with BHE tools, as a secondary cutting structure to provide a solid platform for the BHE device. Many hole-enlargement products are available, each of which fits a particular application. The simplest are the fixed-cutter designs.

Mechanical assessment of an anisotropic conductive adhesive joint of a direct access sensor on a flexible substrate for a swallowable capsule application

Sensor interconnection achieved with Flip Chip (FC) technology and most particularly with Anisotropic Conductive Adhesive (ACA) is a very attractive technique, in achieving a Direct Access Sensor (DAS), in a swallowable diagnostic sensing capsule. This paper describes the work carried out to mechanically characterise the ACA joints when they are inserted in the capsule to determine the smallest capsule diameter that could be used without imparting excessive stress on the interconnect in the DAS integration process for a specific substrate and chip design. Three point inward bending was used to study the effect of the mechanical loading on the joints during the insertion process. The results showed that the insertion force linearly increased and leveled off at a, low friction, constant value. The spring constant of the linear region in a 23mm was 0.2729N/mm and increased to 1.5N/mm for the 15mm diameter hole. It showed that the spring constant decreased linearly as the diameter increased, signifying that for the same distance, less force will be required in a larger diameter hole than in the small diameter holes. During insertion the stress in the assembly, was higher towards the centre of the chip and the window than at the edge of the chip and the ACA fillet. This was characterised by it exhibiting lower voltage values measured in the partial daisy chains that were close to the window rather than the ones that were situated away from the window. The insertion test suggested that the 23mm diameter hole would be the smallest suitable hole for insertion of this assembly. Failure analysis revealed that the depression and the wide crack close to the window imply that the stress was high in this region. The cross sectional analysis showed that failure occurred within silicon/silicon chip pad and that the ACA contacts form a strong joint and was able to withstand the insertion force required to secure the ACA sensor in place before encapsulation.

Analysis of spatial hole burning and temperature effects in vertical-cavity surface-emitting lasers with internal photonic crystal waveguide

We investigate theoretically the effect of two-dimensional photonic crystal (PC) defect waveguide parameters embedded into vertical-cavity surface-emitting lasers (VCSELs) on static operation of PC-VCSEL, including spatial hole burning (SHB) and temperature in the active regions. In structures with larger pitch of PC holes, SHB occurs dramatically and temperature increases in the active region. In large-hole diameter to pitch ratio, SHB has little effect and temperature is decreased in the active regions. We also show that with higher input current, temperature rises and SHB occurs.

A design method of micro-perforated panel absorber at high sound pressure environment in launcher fairings

Abstracts A design method of micro-perforated panel absorbers is proposed for the enhancement of acoustic absorption inside the payload fairings of launch vehicles. An empirical acoustic resistance model of a micro-perforated panel absorber in a high sound pressure environment is suggested to this end. The resistance model is especially appropriate for the launcher fairing application, so that the incident pressure to the surface of bare fairings is considered as a main variable. Other design variables, e.g., the minute hole diameter, the perforation ratio and the thickness of the panel, are also considered in the proposed model. The estimated acoustic resistances and corresponding absorption coefficients are verified by comparing them with the measured results for several micro-perforated panel absorbers having a practical range of parameters. The estimated and measured results show good agreement when the perforation ratio is in the range of 1.4% to 5.3%. The effects of design parameters on the absorption coefficient are discussed. It is demonstrated that the micro-perforated panel absorber with a large hole diameter (about 1.0 mm), which shows a poor sound absorption at low pressure levels, can be a good sound absorber at high incident pressure levels. A set of design charts is provided and this enables one to readily design a micro-perforated panel absorber for the mitigation of acoustic loads in launcher fairings.

디젤 엔진의 인젝터 설계 변수가 노즐 코킹에 미치는 영향 분석

Recent common-rail injector of a diesel engine needs more smaller nozzle hole to meet the stringent emission regulation. But, small nozzle hole diameter can cause nozzle coking which is occurred due to the deposits of post-combustion products. Nozzle coking has a negative effect on the performance of fuel injector because it obstructs the fuel flow inside a nozzle hole. In this study DFSS (Design for six sigma) method was applied to find the effect of nozzle design parameter on nozzle coking. Total 9 injector samples were chosen and tested at diesel engine. The results show that nozzle hole diameter and K-factor have more effect on nozzle coking than A-mass and hole length. Large hole diameter and A-mass, small hole length and K-factor give more positive performance on nozzle coking in these experimental conditions. But, a performance about nozzle coking and exhaust gas emission shows the opposite tendency. Further study is needed to find the relation between nozzle coking and emission characteristic for the optimization of injector nozzle design.

Photonic crystal fiber with W-type effective refractive index profile

The concept of W-type photonic crystal fiber (PCF) was proposed in this paper. Using a full-vector finite element method (FEM), we simulated the promulgate loss property of a specific W-type PCF, which was composed of five hexagonal rings of circular air-holes with a larger hole diameter in the first inner ring. Numerical results show that a suitable designed W-type PCF could exhibit a loss peak on the confinement loss curve, which is different from the standard long wavelength cutoff property of the normal W-type fiber. The center wavelength and the magnitude of the confinement loss peak could be flexibly altered by varying the geometrical structure of the W-type PCF. The specially designed PCF could be of great interest for an in-line fiber filter or other applications.

Glial proliferation after vitrectomy for a macular hole: a spectral domain optical coherence tomography study

To characterize eyes with glial proliferation after macular hole (MH) surgery. We retrospectively reviewed patients who underwent vitrectomy for an idiopathic MH using spectral domain optical coherence tomography (SD-OCT). The pattern of the closed MH after surgery was categorized according to the presence (group 1) or absence (group 2) of apparent glial proliferation, which was determined by glial tissue reflectivity involving the external limiting membrane (ELM) and photoreceptor layers. Photoreceptor layer defect areas were categorized as mild or severe. Best-corrected visual acuity (BCVA) and pre- and postoperative OCT parameters were compared between the two groups. Among 30 eyes followed-up for a median of 11 months, seven (23 %) were assigned to group 1 and 23 (77 %) to group 2. The median age was higher in group 1 (70 years) than in group 2 (63 years). The postoperative BCVA was poorer in group 1 than in group 2 at 3 months and at the final examination (P = 0.022 and P < 0.001 respectively). The median preoperative basal hole diameter in group 1 (1,219 μm) was larger than that of group 2 (590 μm) (P = 0.002). The MH index (hole height/basal hole diameter) was smaller in group 1 than in group 2 (P = 0.012). At the final examination, group 1 had larger mild and severe photoreceptor layer defect areas (medians 1,300 μm and 207 μm respectively) than group 2 (medians 110 μm and 70 μm respectively) (P < 0.001 and P < 0.001 respectively). Eyes with glial proliferation after surgery for MH had different preoperative characteristics than eyes with no evidence of glial proliferation. In addition to a large hole diameter, other factors such as a small MH index and advanced age could be involved in the development of glial proliferation.

Design of Highly Birefringent and Low Confinement Loss Photonic Crystal Fibre by Introducing Asymmetric Defect Structures

Photonic crystal fibres –micro structured fibre consisting of air hole arrays running along its lengthhave attracted much attention for fibre device application because of its unusual optical properties that are not realized in standard optical fibre, such as high birefringence, high nonlinearity, low confinement loss and tailorable chromatic dispersion. High birefringent PCF can be designed by breaking the circular symmetry and implementing asymmetric defect structures such as dissimilar air hole diameter, varying the number of circular and elliptical air holes. This paper proposes a highly birefringent PCF with ultra-low confinement loss by introducing four ring solid core hexagonal structure which having both elliptical and circular air holes and introducing large air hole diameters near the core region for making the asymmetry. The modal birefringence, refractive indices, confinement loss and chromatic dispersion are calculated by using Finite element method (FEM). An endlessly single mode, high birefringent (05.152x10) and a low confinement loss (7.85x10 dB/km) found at the excitation wavelength of λ=1550nm with only four rings of air holes in the fiber cladding.

Physical model test and numerical analysis on the behavior of stratified rock masses during underground excavation

Traditional intensive drilling (or grooving) technology in a roadway destroys the rock mass and supporting structure in the shallow anchoring area while implementing pressure relief. In Dongpang coal mine, it is difficult to avoid the failure of the supporting system and continuous large deformations of the deep roadways influenced by disturbance, despite the application of strong bolt (cable) supporting systems and grouting reinforcements. Therefore, this study proposes a novel “anchoring and pressure relief” synergistic supporting technique to eliminate the dilemma among the anchoring supporting and pressure relief. With strong anchoring supporting in the shallow surrounding rock, this novel technology realizes pressure relief by excavating large-diameter holes in the deep peak stress area, to enable active regulation of the move of the peak stress area to the deep surrounding rock without impairing the shallow anchoring area. The path of coal body rheology and stress move is cut off by large-diameter holes using this novel technology, achieving the purpose of absorbing energy and deformation, decreasing the stress applied on the supporting structure in the anchoring area. The novel technology effectively solves the control problems of continuous large deformation in deep roadway and has a good engineering application prospect. This study findings will add scientific value for the improvement of surrounding rock control of deep roadway.

Utilizing an In-Process Automatic Tool Change for Drilling and Reaming Large Diameter Holes

A drill/ream cycle is necessary to produce high quality, large diameter holes in carbon-titanium stacks. Manual tool changes and traditional automatic tool changers limit hole-tohole cycle times and hole quality. An in-process tool changer, mounted directly on the machine head, replaces a cutting tool with a reaming tool while clamp-up is maintained on the aircraft panel. By reducing or eliminating operator intervention, machine-axis moves, and optical resynchronization, an in-process automatic tool changer shortens cycle time, improves hole quality, and increases positional accuracy of holes. Automating this process also reduces risk of harm to the operator and aircraft structure.

Research on New Machining Method that Cutting Arc Surfaces in SIEMENS840D System

Analyzed the commonly used method that machined large diameter hole bottom transition arc surface, it’ advantages and shortcoming. Through an example, we introduced the method of using the R parameter programming of SIEMENS840D numerical control system when milling cut large diameter transition arc surfaces. This method's application has the positive significance to reduce the programming and other non-productive work time, guaranteed processing quality, raised the machining efficiency, so we introduce this method and hope it is helpful to machining of similar parts.

Hole-Within-a-Hole Method for Determining Residual Stresses

The strain gauge rosette hole drilling method is often used for determining residual stresses versus depth to depths on the order of 0.5–1.5 mm. Frequently, it is of interest to find stress profiles to greater depths. To provide such a capability, a new approach is presented. Residual stresses versus depth are found by drilling a small diameter hole incrementally to a depth of half of its diameter. The profile of stresses versus depth is found from changes in surface displacements associated with the stress relief from introducing the hole, observed by optical means. Next, a larger diameter, square-bottomed hole is milled directly over the small hole to a depth equaling that of the smaller diameter hole. The bottom of the larger hole provides a fresh surface for optical observation and incremental drilling of a new small hole. This procedure is repeated until a desired total depth is reached. A computational approach is described for correcting the stresses found from the small holes to account for the perturbation of stresses by the material removed by the larger diameter hole. Results of applying this method to find stresses versus depth in a plate subject to uniaxial bending stress and a plate with biaxial residual stresses that vary from compression to tension through the thickness are shown.

Investigation of V-type photonic crystal fiber with high birefringence

According to the full-vector finite element method, a new kind of V-shape photonic crystal fiber with high birefringence is proposed. Simulation results show that the V-shape photonic crystal fiber has a birefringence of 1.239×10-2 at a wavelength of 1.55 μm, when its cladding air hole pitch, large air hole diameter, small air hole diameter are 1.0 μm, 0.95 μm and 0.6 μm, respectively. There are two zero dispersion wavelengths in the visible and the near-infrared region respectively, and the abnormal dispersion zone includes the operation wavelength of Ti:sapphire laser, which is advantageous for nonlinear generation of photonic crystal fibers. The difference in air filling fraction between fast and slow axis can be used as a sensor for the weak strain.

Enhanced photoluminescence from condensed electron-hole pairs in trenched Si

In this paper, we report the characteristics of low-temperature photoluminescence (PL) from condensed electron-hole (e-h) pairs in p-type silicon substrates with and without high-aspect-ratio trench structures. The average hole diameters of trenches were 140 and 170 nm, and the depth of trenches were about 5 μm. An Al2O3 surface passivation layer with thickness of 10 nm was grown by atomic layer deposition on surfaces of all samples to reduce nonradiative recombination and provide nucleation centers of condensed e-h pairs at Si/Al2O3 interface. Significant enhancement of PL intensity from e-h liquid/droplet (EHL/EHD) was observed in the trenched silicon at temperature below 30 K. Dominant PL from EHL/EHD at 14 K in the trenched silicon with larger hole diameters may be attributed to stronger spatial confinement of condensed e-h pairs in a smaller volume.

Field Note: Successful Establishment of a Phytoremediation System at a Petroleum Hydrocarbon Contaminated Shallow Aquifer: Trends, Trials, and Tribulations

We report the establishment of a mixed hybrid poplar (Populus spp.) and willow (Salix spp.) phytoremediation system at a fuel-contaminated site. Several approaches were used to balance competing goals of cost-effectiveness yet successful tree establishment without artificial irrigation or trenching. Bare root and unrooted cuttings were installed using either: (1) 1.2 m deep holes excavated with an 8 cm diameter auger using a direct-push rig and backfilled with the excavated, in situ soil; (2) 1.2 m deep holes created with a 23 cm diameter auger attached to a Bobcat rig and backfilled with clean topsoil from offsite; and (3) shallow holes between 15–30 cm deep that were created with a 1.3 cm diameter rod and no backfill. Tree mortality from initial plantings indicated contaminated zones not quantified in prior site investigations and remedial actions. Aquifer heterogeneity, underground utilities, and prior remediation infrastructure hampered the ability of the site to support a traditional experimental design. Total stem length and mortality were measured for all planted trees and were incorporated into a geographic information system. Planting early in the growing season, augering a larger diameter hole, and backfilling with clean, uncontaminated topsoil was cost effective and allowed for greater tree cutting growth and survival.