Back Angle Research Articles

Improving Rate of Penetration for PDC Drill Bit Using Reverse Engineering

In petroleum industry, drilling is one of the most important aspects due to its economics. Reduction in drilling time is desired to minimize operations cost. This work focus on Polycrystalline Diamond Compact (PDC) drill bit which is categorized as a fixed cutter drilling bit. Problem such as wear and tear of PDC cutter are some of the main factors in drilling process failure affecting the rate of penetration (RoP). Thus, an intensive study in drill bit design could potentially save costs if the drill bit efficiency can be improved. The objective of this research is to improve the PDC cutter design and analyse design improvement in relation to the rate of penetration using reverse engineering (RE) approach. RE method is capable of resolving unavailable drill bit blueprint from the manufacturer due to propriety and confidential. RE non-contact data acquisition device, 3D laser scanner will be used to obtain cloud data of the existing worn drill bit. Computer Aided Design (CAD) software is used to convert cloud data of the PDC drill bit into 3D CAD model. Optimization of PDC Drill bit is focused on feature design such as back rake angle, side rake angle and number of cutters. CAE software is used to analyse the effect of the design feature modification to rate of penetration. Results show rate of penetration increases as the angle of both rake angle and number of cutter decreases.

Методика проектирования сборных токарных резцов, оснащенных СМП с нулевым задним углом

Методика проектирования сборных токарных резцов, оснащенных СМП с нулевым задним углом

Valve Plate for Piston Pump Cavitation Problem with the Damp Groove Structural Optimization

To reduce the cavitation occurring on valve plate of typical Swashplate piston pump, an optimization design method was introduced to quantitively analyse the accurate relationship between structural jet grooves parameters and cavitation.Using the CFD method, the sunking and discharging process in piston pump was simulated dynamically.The damp grooves structure effect on both jet angle and pressure shock were analysed visually with a series of different parametrical grooves.By establishing parametrical damp groove model, the piston pumps dynamic analysis was integrated with the technologies of CFD analysis, experimental design and approximation model, etc.The mathematical model of plunger pressure in oil back period, jet angle and structural parameters of damp groove were established in the form of second-order RSM model. The damp groove structure of valve plate was optimized on the basis of the RSM model.Test data show that the anti-cavitation performance of optimized valve plate was increased obviouslyAnd this method provided theoretical foundation for the structure design of damp groove.

Spiral Bevel Gears with Optimised Tooth-end Geometry

Industrially-manufactured, spiral bevel gears with complementary tooth-end surfaces as a rule have reduced tooth thickness and subsequently reduced strength at the tooth ends. The weakened tooth ends of octoid gearing are generally produced by machining, inevitably resulting in a certain lengthwise dimensional discrepancy and slight profile difference. This in turn very often leads to systematic breakage of teeth. Serious, systematic damage occurs irrespective of the transmission tightness of the outer or inner tooth ends.Gear manufacturers currently use several solutions to avoid such breakages, including artificial inclination near to the teeth or deliberately reducing the back or outer cone angle and increasing the front or root cone angle.This paper outlines an improved design of gear blanks, with optimised tooth ends. Our research concluded that it is possible to optimise rectangular-generated, spiral bevel pinion/gear pairs with constant tooth height and a common pitch cone apex. We can successfully achieve this through recalculation of the gear blanks, without any changes in the flank geometry or tooth-cutting process. Thus the gear pair with optimised tooth ends can be cut without interference to the customary tooth-cutting process. To prove the concept, an example of the recalculation is provided. These improvements result in increased tooth strength, simplification of the gear blank geometry and more suitable geometry for modern machining, as well as a smaller outer diameter of the gear.

Wear characteristics of nano-polycrystalline diamond tool in cutting of tungsten carbide

Nano-polycrystalline diamond is a binderless diamond synthesised by the direct conversion of graphite under high pressure and high temperature. This diamond has the same or higher hardness than synthesised monocrystalline diamond and is expected to be an effective material for cutting tools. In this study, the cutting of tungsten carbide was conducted using two monocrystalline diamond tools, a chemical vapour deposition (CVD) diamond tool and a nano-polycrystalline diamond tool to investigate their wear characteristics in terms of the diamond structure and composition. A supply of chemical solution coolant resulted in a stable machined surface, and a negative back rake angle of 30° was shown to provide the minimum tool wear and machined surface roughness. The nano-polycrystalline diamond tool shows excellent wear resistance superior to those of the two monocrystalline diamond tools and CVD diamond tool in continuous cutting as well as better wear resistance than the CVD diamond tool in intermittent cutting.

Optimal machining conditions for turning Ti-6Al-4V using response surface methodology

Machining titanium is one of ever-increasing magnitude problems due to its characteristics such as low thermal conductivity, modulus of elasticity and work hardening. The efficient titanium alloy machining involves a proper selection of process parameters to minimize the tangential force (F z) and surface roughness (R a). In the present work, the performance of PVD/TiAlN coated carbide inserts was investigated using response surface methodology (RSM) for turning Ti-6Al-4V. The effects of process parameters such as speed (v), feed (f), depth of cut (d) and back rake angle (γ y ) on F z and R a were investigated. The experimental plan used for four factors and three levels was designed based on face centered, central composite design (CCD). The experimental results indicated that F z increased with the increase in d, f and decreased with the increase in v and γ y , whereas R a decreased with the increase in v and γ y , and increased with d and v. The goodness of fit of the regression equations and model fits (R 2) for F z and R a were found to be 0.968 and 0.970, which demonstrated that it was an effective model. A confirmation test was also conducted in order to verify the correctness of the model.

Characterization of Vertebral Angle and Torso Depth by Gender and Age Groups With a Focus on Occupant Safety

Objective: The human body changes as it becomes older. The automotive safety community has been interested in understanding the effect of age on restraint performance. Focus has been placed on characterizing the body's structural changes associated with age and gender. In this study, spine alignment and torso depth were assessed, because both variables have been shown to affect injury risk. Methods: The data was obtained from computed tomography (CT) scans of more than 24,000 patients aged 16 and older. The data consisted of thoracic and lumbar vertebral angles relative to a fixed plane, as well as vertebra-to-front skin and spine-to-back skin distances. Angle measurements were taken in the sagittal plane at each vertebra level from T1 to L5; distance measurements were taken from T6 to L5. The data were analyzed as a function of gender and age with the young group defined as 16 to 29 years old and the older group as 75 and up. Results: Vertebral angles were different depending on location. They varied from −24.5 ± 8.9° at T2 to 12.2 ± 5.6° at L1. The vertebral angles also varied with age. Angles in the older male group were 1.74 times larger at T1 and 2.03 times larger at T7 than in the young male group. Similar findings were observed for females. The effect of age and gender was modeled with forward/backward selection using a regression model. The vertebra-to-front skin distance also differed depending on vertebral level. It was highest at T10 at 162.5 ± 30.9 mm and lowest at L4 at 125.3 ± 37.3 mm for the entire study population. On average, males had larger distances than females. The spine-to-back distances were greatest in the lumbar area. The spine-to-back distance increased with lower vertebral level, regardless of age. The vertebral angle and distance data were analyzed for a male subgroup approximating the height and weight of a 50th percentile male dummy. The results showed that the vertebra-to-front skin distance increased with age. There was not a clear trend for the spine-to–back skin distance and L1 vertebral angle. Conclusions: The changes in the vertebral angles, as well as the anterior and posterior spine-to-skin distances along the sagittal plane, were determined as a function of age and gender. The effect was greatest in the mid-thoracic area. Spine alignment and body shape differences need to be considered in human mathematical models used to develop safety countermeasures for the older population, because they may affect the loading path and lead to different seating postures or belt positioning. Supplemental materials are available for this article. Go to the publisher's online edition of Traffic Injury Prevention to view the supplemental file.

An Experimental Assessment of the Effects of Stator Vane Tip Clearance Location and Back Swept Blading on an Automotive Variable Geometry Turbocharger

Off-design performance is of key importance now in the design of automotive turbocharger turbines. Due to automotive drive cycles, a turbine that can extract more energy at high pressure ratios and lower rotational speeds is desirable. Typically a radial turbine provides peak efficiency at U/C values of 0.7, but at high pressure ratios and low rotational speeds, the U/C value will be low and the rotor will experience high values of positive incidence at the inlet. The positive incidence causes high blade loading resulting in additional tip leakage flow in the rotor as well as flow separation on the suction surface of the blade. An experimental assessment has been performed on a scaled automotive VGS (variable geometry system). Three different stator vane positions have been analyzed: minimum, 25%, and maximum flow position. The first tests were to establish whether positioning the endwall clearance on the hub or shroud side of the stator vanes produced a different impact on turbine efficiency. Following this, a back swept rotor was tested to establish the potential gains to be achieved during off-design operation. A single passage CFD model of the test rig was developed and used to provide information on the flow features affecting performance in both the stator vanes and turbine. It was seen that off-design performance was improved by implementing clearance on the hub side of the stator vanes rather than on the shroud side. Through CFD analysis and tests, it was seen that two leakage vortices form, one at the leading edge and one after the spindle of the stator vane. The vortices affect the flow angle at the inlet to the rotor, in the hub region. The flow angle is shifted to more negative values of incidence, which is beneficial at the off-design conditions but detrimental at the design point. The back swept rotor was tested with the hub side stator vane clearance configuration. The efficiency and MFR were increased at the minimum and 25% stator vane position. At the design point, the efficiency and MFR were decreased. The CFD investigation showed that the incidence angle was improved at the off-design conditions for the back swept rotor. This reduction in the positive incidence angle, along with the improvement caused by the stator vane tip leakage flow, reduced flow separation on the suction surface of the rotor. At the design point, both the tip leakage flow of the stator vanes and the back swept blade angle caused flow separation on the pressure surface of the rotor. This resulted in additional blockage at the throat of the rotor reducing MFR and efficiency.

Optimum Design of a Screw-In Venturi Flow Sensor

To study discharge coefficient linearity of screw-in venturi flow sensor, the effect of the screw-in blade attached to the sensor on discharge coefficient was analyzed, the structure of the screw-in blade was optimized by CFD software. Through the observation of velocity field, it was found that discharge coefficient will basically remain unchanged at low Reynolds number, while it declines greatly at high Reynolds number because of the guidance of the screw-in blade, as a result discharge coefficient linearity becomes better at the same measurement range. Orthogonal array of DN100 was designed for 10:1 measurement range to explore effect of geometric parameters of the screw-in blade on discharge coefficient linearity. Optimum structure for the screw-in blade is determined as follows: number of blade is 4, back slip angle of blade is 50°, front slip angle of blade is 5° and height of blade is 10.5mm. The numerical simulation indicates discharge coefficient linearity of the optimal screw-in venturi flow sensor is 0.601%,which is better than that of double-cone venturi flow sensor.

Is the Movement of the Thoracolumbar and Lumbosacral Joints in the Ridden Dressage Horse Affected by Muscle Development?

IntroductionStabilisation of the back is essential for rider support and to moderate intervertebral movement. Epidemiological data has shown that 25% of UK dressage horses had back pain over a 2‐year period (Murray et al. ). It has been established that back pain in sports horses is performance limiting (Stubbs et al. ). Intervertebral range of motion (ROM) and flexion–extension movements of the back have been previously described. However, the relationship between muscle development and ridden ROM has not been investigated.AimsTo investigate the relationship between grade for development of muscles visible on examination and ridden ROM of the thoracolumbar (TL) and lumbosacral (LS) regions of the back.MethodsThirty‐five dressage horses (novice to Grand Prix competition level) were evaluated by an experienced clinician and assigned muscle development grades. High‐speed motion‐capture (250Hz) was used to measure TL and LS angle for 4 strides of collected trot from the left side. Spearman's rank correlation tests were used to test for associations between muscle development grade and ridden angles and ROM.ResultsIncreased development of visible muscle groups was correlated with increased TL and LS flexion at different parts of the stride (Table ). Decreased LS ROM was associated with increase muscle development of the thoracic and lumbar regions.Conclusions and practical significanceResults suggest that increased development of muscle groups visible on examination is important for stabilising the TL and LS regions. Back stabilisation is likely to help support the rider's weight and be involved in protection of the small joints and ligaments of the back. These findings support evaluation of the musculature during a veterinary examination as a guide to TL and LS stability, and the potential importance of visible muscle development in prevention and rehabilitation of ridden back problems.Ethical animal researchStudy approved by AHT Ethical Review Committee. Sources of funding: Funding from the Elise Pilkington Charitable Trust, British Dressage and Dr Wilfrid Bechtolsheimer. Competing interests: None. Table summarising association of muscle development grade with back angles at specific points of the stride within the hindlimb (HL) and forelimb (FL) Angle Point of stride Muscle group Thoracolumbar (TL) HL stance Lumbosacral, pelvic HL maximum protraction Neck, lumbar, lumbosacral, pelvic FL stance Neck, lumbar, lumbosacral, pelvic Lumbosacral (LS) HL stance Abdominal, thoracic, lumbar, lumbosacral, pelvic, hindlimb HL maximum protraction Abdominal FL stance Abdominal, lumbosacral, hindlimb

Emergency Medical Services

Emergency medical service workers are a high-risk group, and while some of this risk is inherent in the type of work that they perform, much of it may be avoidable. This study examines medical professionals administering patient care during patient transportation to highlight previously overlooked safety issues in an ambulance. EMS workers were observed over the course of 3 months using video data collected during all patient transports. Visual data reduction recorded the medic back angles, seated/standing posture, and whether or not the medic was providing patient care during all patient transports. Analysis of the data showed that EMS workers display intermediate (between 20° and 60°) and severe (larger than 60°) back angles while standing compared to sitting, and are standing and displaying potentially harmful postures while providing patient care. These findings indicate that there is a relationship between the EMS worker’s ability to adequately provide patient care and his inability to do so from a neutral seated posture in an ambulance layout that is currently used in many ambulances used throughout the world.

Seismic stability of reinforced soil walls under bearing capacity failure by pseudo-dynamic method

In order to evaluate the seismic stability of reinforced soil walls against bearing capacity failure, the seismic safety factor of reinforced soil walls was determined by using pseudo-dynamic method, and calculated by considering different parameters, such as horizontal and vertical seismic acceleration coefficients, ratio of reinforcement length to wall height, back fill friction angle, foundation soil friction angle, soil-reinforcement interface friction angle and surcharge. The parametric study shows that the seismic safety factor increases by 24-fold when the foundation soil friction angle varies from 25° to 45°, and increases by 2-fold when the soil-reinforcement interface friction angle varies from 0 to 30°. That is to say, the bigger values the foundation soil and/or soil-reinforcement interface friction angles have, the safer the reinforced soil walls become in the seismic design. The results were also compared with those obtained from pseudo-static method. It is found that there is a higher value of the safety factor by the present work.

Implementation and Design of Basketball Technical Action Based on B/S Framework Data Mining System

Basketball is a technical sport, and players' shooting action will affect the basketball hit rate, which affects the players' performance and competition results. Therefore, in the process of usual training, players should strengthen the basketball technology actions, under this background, the shooting action of basketball players are optimized. The basketball players are shooting, body lean back angle, release angle and release initial velocities as research object, the use of the B/S frame data mining system develops basketball shooting skills and competition information framework model, and the use of eight quantile statistics method determines the membership function, establishing the association of basketball technology actions and marks, according to the association index, it can successfully optimize design of the basketball shooting parameters.

Design of High-Efficient Bits for Igneous Rock in Xushen Gasfield

The igneous rocks in deep formations of the Xushen gasfield have the following characters: high abrasive property, high hardness, and high drillability, which lead to many drill bit accidents, few footage per bit , low efficiency of drilling, long drilling cycle, these severely restrict the exploration and development process of gas field. According to the features of deep formation, a hybird cutters bit is designed. It has three cones, with the overhang cone , duplicate taper and offset cone characters. The tungsten carbide cutters and the polycrystalline diamond compacts cutters are alternative collocation in the same tooth row in the bit. The exposed height of the tungsten carbide cutters is higher than polycrystalline diamond compacts cutters. The back rake angle of polycrystalline diamond compacts cutters is 10 ~ 40 °, the side rake angle is 10 ~ 30 °. The normal direction of working face stay the same with the composite slip direction, and the side rake pointed at adjacent gullet. Through the design method, it is integrated that the advantages of roller bit and PDC bit, the way of impact breakage and rotational shear breakage and the prominent performance of tungsten carbide cutters and polycrystalline diamond compacts cutters. It can improveROP and bit life.

Ergonomically adjustable school furniture for male students

The need for adjustability in school furniture, in order to accommodate the variation in anthropometric measures of different genders, cultures and ages is becoming increasingly important. Four chair-table combinations, different in dimensions, with adjustable chair seating heights and table heights were designed, manufactured and distributed to schools in Riyadh city. The number of the student participants was 28 (6 to <9 years), 30 (9 to <12 years), 30 (12 to <15 years) and 30 (≥ 15 years) in first, second, third and fourth age-group sets respectively. Muscular activity signals (EMGs) for both neck dorsal muscles and upper trapezius muscles, posture measures in terms of neck angle, viewing angle, back angle and discomfort ratings were considered as dependent factors. New designed adjustable sets versus current sets available in the schools were the independent variables. The results indicated that EMGs signals for both neck dorsal and upper trapezius muscles in the new sets were significantly lower when compared to the current sets. The three posture measures associated with the new sets were significantly improved when compared to the current sets. Finally, the participants' ratings of discomfort were significantly low for sitting on the new sets compared to sitting on the current sets. Key words: School furniture, adjustable seat, EMG, discomfort rating, anthropometry

Cutting Force Model for Diamond Cutting Microstructured Surfaces

The depth of cut changed periodically along the contour of the cutting surfaces. The diamond tool of sharp point tip was used in diamond cutting microstructured surfaces with Fast Tool Serve (FTS). All reported the cutting force model were not suitable for accurately predicting cutting force. A cutting forces model concerned with edge radius, spring back and dynamic shear angle was proposed for diamond cutting microstructured surfaces. The model was verified with a series of experimental results. The results showed that the proposed model was able to exactly predict the cutting force.

Analysis of plastic deformation behavior during back pressure equal channel angular pressing by the finite element method

It is generally known that equal channel angular pressing with back pressure (BP-ECAP) not only applies higher hydrostatic stress and more deformation compared to what a regular ECAP can apply to a workpiece, but also prevents surface defects in the workpiece during the processing. In this study, the plastic deformation behavior of the materials during the BP-ECAP process was investigated using the finite element method. The homogeneity within the workpiece was analyzed in terms of contours, path plot, and statistics of strain distribution under different conditions regarding back pressure, strain hardening, friction, and corner angle. The simulation results shed some lights on the optimum design of ECAP for homogeneous and large severe plastic deformation.

Application of Interactive Orthogonal Design on the Aerodynamic Drag Optimization of Hatchback Car

The interactive orthogonal design was employed to investigate the aerodynamic drag coefficient (CD) of hatchback car by using CFD methods. And the effects of back windshield angle, diffuser angle, front windshield angle, hood angle, side windshield angle and tail length were discussed. The results indicates that back windshield angle, diffuser angle and their interaction, hood angle and front windshield angle have notable effect on the CD of the model, while other parameters and interactions have no notable effect. The best CD conditions are: back windshield angle 20°/60°, diffuser angle 12°, front windshield angle 30°, hood angle 15° and tail length 4300mm.

20~30대 하체비만형 여성을 위한 양방향 스트레치 팬츠 원형 개발

This research was carried out on women in their 20s and 30s who have overweight lower body. The subjects selected for this study were women a Rohrer index of 1.6 or higher, a waist circumference 78.5cm to 83.5cm, and a lower drop of at least 18cm. The aim is to propose a prototype of bi-stretch pants meeting demands for both functionality and aesthetic appeal. Various clothing patterns ease amount of the waist and hip circumferences and crotch depths and were developed. They had different crotch widths, and center back line angles. The results showed that the best pants patterns were ease 1cm to the total hip circumference. The front hip circumference was H/4-0.5cm, and the back hip circumference was H/4+1cm. The front crotch width was H/20+1cm, the back crotch width was H/10+3cm. No additional ease was given to the total waistline. The front waist circumference was W/4+0.5cm. The back waist circumference was W/4-0.5cm. The knee circumference was set at 44cm, the pant hem width was set at 36cm, and the pant length was set at 100cm-5cm. The findings of this research can be used as basic data for stretch pants that fit the abdomen, hips, and thighs for women in their 20s and 30s with overweight lower body.

Distribution of Belt Anchorage Locations in the Second Row of Passenger Cars and Light Trucks

Seat belt anchorage locations have a strong effect on occupant protection. Federal Motor Vehicle Safety Standard (FMVSS) 210 specifies requirements for the layout of the anchorages relative to the seating reference point and seat back angle established by the SAE J826 H-point manikin. Sled testing and computational simulation has established that belt anchorage locations have a strong effect on occupant kinematics, particularly for child occupants using the belt as their primary restraint. As part of a larger study of vehicle geometry, the locations of the anchorage points in the second-row, outboard seating positions of 83 passenger cars and light trucks with a median model year of 2005 were measured. The lower anchorage locations spanned the entire range of lap belt angles permissible under FMVSS 210 and the upper anchorages (D-ring locations) were distributed widely as well. Combined with the findings from concurrent research on the effects of belt geometry, these results suggest that occupant kinematics in frontal impact can be expected to differ widely across vehicles due to differences in belt geometry. Language: en