Papers by Keyword: Deep Hole Drilling (DHD)

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Authors: S. Nakhodchi, Gabrielle Hilson, David John Smith, Peter E.J. Flewitt
Abstract: In this paper the challenges associated with the determination of within section macrostresses in the non-metallic materials porous reactor core graphites, glasses and thermally grown oxides, will be considered, with respect to the length-scale over which such measurements are required. Examples are briefly presented to demonstrate the capability of the methods selected, which include deep hole drilling and photoluminescence and Raman spectroscopy. These techniques span the length-scale from micro-metres to tens of millimetres. The measured values will be discussed with respect to the confidence with which these techniques may be applied and hence benefits for life/integrity evaluation.
Authors: Peng Hai, H.X. Wei
Abstract: Near-dry deep hole processing technology is a kind of technology which dry cutting technology is applied to deep hole processing to save energy and decrease environmental pollution. In this paper, the structure and work principle of near-dry deep-hole drilling system were introduced and the cutting mechanism of near-dry deep-hole drilling was analyzed which include the mechanism of cutting fluid atomization and flow, the mechanism of atomized cutting fluid cool and lubricate, and the mechanism of separating chips into short pieces and discharge chips by air stream, etc. The mathematical mode of gas-liquid two-phase flow of atomized cutting fluid in drilling shaft and the cooling and lubrication mechanism of the capillary in cutting zone were introduced. It is found that near-dry deep hole processing has better cooling and lubrication effect through experiments.
Authors: W.R. Mabe, W.J. Koller, A.M. Holloway, P.R. Stukenborg
Abstract: This paper presents the results of an experimental validation of the deep hole drill residual stress measurement method. A validation test specimen was fabricated and plastically loaded to impose a permanent residual stress field within the specimen. The validation test specimen was designed to provide a variety of stress profiles as a function of location within the specimen. A finite element analysis of the validation test specimen was performed in order to provide a reference solution for comparison to the deep hole drill experimental results. Results from experimental testing of the validation test specimen agree well with the finite element analysis reference solution, thereby providing further validation of the deep hole drill method to measure residual stresses.
Authors: H. Peng, Jiang Ping Wang, Ze Fu Bao
Abstract: This paper depicts a boring and trepanning association (BTA) deep-hole drilling system with near-dry cutting technique. The cutting tests are carried out in view of the machining performances under the condition of applying the compressed air and atomized cutting fluid for drilling deep holes on titanium alloy which is difficult to cut. Several cutter materials have been utilized in the tests. The reasonable material of the deep-hole drilling cutter has been determined by analyzing the cutting force, the cutter wear and the surface finish. Environmental pollution decreases owing to little cutting fluid consumption in near-dry cutting system.
Authors: H.B. Zhao, Y.F. Nan
Abstract: The near-dry deep hole drilling system was taken as object in this study,and the contrast experiment between the deep hole drilling system and the traditional(wet)deep-hole drilling system,including the cutting force,the tool wear,the surface quality and the chip-break have been done. The results show that the near-dry system drill stability and have better effort in cooling,lubrication,chip removal effective. The tool life and surface quality within the hole are better,at the same time,it can greatly reducing the amount of cutting fluid,the costs and the pollution of the environment. So we can get a conclusion that it is an ideal system in green drilling process.
Authors: Lin Zhu, Xin Chen, Bernd Viehweger
Abstract: γ-titanium aluminide is a new intermetallic structural material. γ-titanium aluminide alloy has the advantages of high temperature resistance, high performance of anti-oxidation effect, low-density, high specific strength and rigidity etc. But high strength, hardness and brittleness of the material also make processing difficultly. High cutting force and cutting temperature affecting a decline in cutting lifetime and cutting efficiency. This problem is more acute in deep hole drilling. In this paper, we have analyzed the cutting performance of γ-titanium aluminide and designed a deep-hole drills with appropriate tool material and geometric parameters. The experimental result shows: this drill bit is stable and efficient in drilling and can achieve a good quality.
Authors: Bruce L. Tai, David Stephenson, Steven White, Albert Shih
Abstract: This study investigates the effect of air pressure on workpiece temperature in through tool minimum quantity lubrication (MQL) deep-hole drilling. Experiments on 200 mm deep holes drilled by a 10 mm carbide drill were conducted under regular (500 kPa) and high (1000 kPa) air pressure conditions. Torque data shows that the chip clogging problem occurring under regular air pressure can be solved by the high air pressure. An inverse heat transfer method is utilized to quantify the heat fluxes and calculate the temperature distribution during drilling based on embedded thermocouples along the depth. Results show that temperature around the hole increases rapidly when the chips start accumulating in the hole under regular air pressure and cause high heat flux on the drilled hole wall surface. The high pressure condition, prevents chip accumulation, thus reducing the total heat flux.
Authors: X. Ficquet, Christopher E. Truman, David John Smith
Abstract: The paper presents the results of residual stress measurements on a ferritic steel plate containing a repair weld. The repair was considered representative of that found in the secondary circuit piping in power plant. The paper primarily uses the deep hole drilling (DHD) technique, but compares results found by this technique with those obtained using neutron diffraction. Both sets of measurements confirmed that highly tensile residual stresses exist in the repair weld. The two measurement techniques produced results that were in acceptable agreement, but the neutron diffraction results were consistently higher than the deep hole drilling results. It was thought this was due to the use of a constant stress-free lattice parameter d0 .
Authors: D.M. Goudar, Mark Turski, Suzanne Clitheroe, Ed J. Kingston, Chris Gill, Philip J. Withers, David John Smith
Abstract: This paper examines the extent to which mechanical shot peening (MSP), ultrasonic impact treatment (UIT) and laser shock peening (LSP) can affect the tensile residual stresses in the fusion zone caused by welding for a 10mm multi-pass 'V' groove weld within a 20 mm thick 304L stainless steel plate. Stresses are measured by deep hole drilling, neutron diffraction and incremental center hole drilling. For the UIT and LSP treated samples, the tensile stresses present in the as-welded plate are reversed to compressive stresses to a depth in excess of 2-4mm. For MSP the affected depth is much less (~0.5mm). The depth of these compressive stresses is similar to those measured in 20 mm thick parent plate test coupons.
Authors: D.M. Goudar, Ed J. Kingston, Mike C. Smith, Sayeed Hossain
Abstract: Frequent failures of the pressuriser heater tubes used in Pressurised Water Reactors (PWRs) have been found. Axial cracks initiating from the tube outer diameter have been detected in some tubes as well as the resulting electrical problems. Replacement of the heater tubes requires an undesirably prolonged plant shutdown. In order to better understand these failures a series of residual stress measurements were carried out to obtain the near surface and through-thickness residual stress profiles in a stainless steel pressuriser heater tube. Three different residual stress measurement techniques were employed namely, Deep-Hole Drilling (DHD), Incremental Centre Hole Drilling (ICHD) and Sachs’ Boring (SB) to measure the through thickness residual stress distribution in the heater tubes. Results showed that the hoop stresses measured using all three techniques were predominantly tensile at all locations, while the axial stresses were found to be tensile at the surface and both tensile and compressive as they reduce to small magnitudes within the tube. The magnitude of the in-plane shear stresses was small at all measurement depths at all locations. The various measurement methods were found to complement each other well. All the measurements revealed a characteristic profile for the through-thickness residual stress distribution.
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