Axis Inclination Angle Research Articles

Mechanical and technological aspects of micro ball end milling with various tool inclinations

This paper is focused on the evaluation of mechanical and technological aspects of the micro ball end milling of hardened TOOLOX 44 steel. The experiment includes the measurement of acceleration of vibrations during the micro milling tests with variable feed per tooth and tool's axis inclination angle values. The next step involves the analysis of dynamics, based on the determination of measured signals’ statistical measures and Fast Fourier Transform (FFT). This stage includes also the prediction of micro ball end milling forces on the basis of mechanistic model considering run out, variable edge forces, and kinematics of low radial immersion milling with tool axis inclination. Subsequently, the optimization of the micro ball end milling process is conducted. This procedure is carried out by the minimization of process responses with the application of a method based on the minimization of total desirability function. In the last stage, the obtained optimal values of tool's axis inclination angle and feed per tooth are validated during the micro milling tests involving the measurements of machined surface roughness. Research reveals that micro ball end milling with the optimally selected tool's axis slope along the toolpath and feed per tooth affects the minimization of milling vibrations and improvement in surface finish.

Analysis of scavenge port designs and exhaust valve profiles on the in-cylinder flow and scavenging performance in a two-stroke boosted uniflow scavenged direct injection gasoline engine

In this study, effects of intake scavenge port designs and exhaust valve opening profiles were studied on the scavenging process in a newly proposed two-stroke boosted uniflow scavenged direct injection gasoline engine by detailed three-dimensional engine simulations. As the most important geometric parameters, the axis inclination angle and swirl orientation angle of scavenge ports, as shown in Figure 1, were investigated and optimized for best scavenging performances at first. With the optimal axis inclination angle of 90° and swirl orientation angle of 20°, various combinations of scavenge port opening timing, exhaust valve opening duration and exhaust valve opening timing were then analysed. Four distinct scavenging periods, that is, early backflow period, backflow scavenging period, main scavenging period and post backflow period, were identified and their impacts on the in-cylinder flow motions and scavenging performances were investigated. The results show that the optimal scavenging performance can be achieved with a higher delivery ratio, charging efficiency and scavenging efficiency when the post backflow is just avoided by tuning the difference between the closing timings of scavenge ports and exhaust valves (Δ close) and the overlap between the opening profiles of scavenge ports and exhaust valves (Δ overlap) for a specific exhaust valve opening duration. A longer exhaust valve opening duration can be used to further improve the scavenging performances. In addition, the difference between the opening timings of scavenge ports and exhaust valves (Δ open) can be increased to improve scavenging efficiency. The Δ close also shows strong positive correlation with in-cylinder swirl ratio and negative correlation with tumble ratio. The results presented in this study provide the fundamental knowledge of the scavenging process in the uniflow scavenged two-stroke engine and assist the design of scavenge ports and valve strategies to optimize in-cylinder flow motion and scavenge performances in the two-stroke boosted uniflow scavenged direct injection gasoline engine with a variable valve actuation system for exhaust valves.

Influence de la réconstruction du ligament radio-dorsal sur la stabilité de l’articulation trapeziometacarpien

Introduction Biomechanical and anatomical research has shown that the dorsal radial ligament (DRL) is thicker and stiffer then the anterior oblique ligament (AOL). The DRL as the key stabilizing structure of the trapeziometacarpal (TMC) joint has been documented extensively. The aim of the current study is to quantify the influence of a surgical DRL reconstruction on TMC stability in non-traumatic instability patients. Methods Eight patients with symptomatic TMC instability but no radiographic signs of osteoarthritis were recruited and dynamic CT scans of the thumb were made during active abduction-adduction, flexion-extension and two functional grip task using a radiolucent jig. After image acquisition and segmentation, metacarpal translation was expressed relative to the trapezial articular surface. In addition, intersection points and inclination angles of instantaneous helical axes with an anatomically defined plane were determined to facilitate motion comparison between subjects. Scans were acquired before and 6–12 months after reconstruction of the DRL. Results During active motion, there is motion at both the trapeziometacarpal (TMC) and trapezioscaphoid (STT) joints. However, joint motion patterns, defined as changes in helical axis inclination angles during opposition, differ between patients. In most patients, dorsal luxation of the first metacarpal (MC1) could be clearly seen and quantified during the full range of motion, as well as during function grip tasks. Furthermore, dorsal luxation results in higher point loading of TMC cartilage as could be demonstrated by mapping the changes in articular contact area for each active motion. After DRL reconstruction, patients report improvement in pain and subjective stability in the joint. Analyses of the dynamic CT scans demonstrate reduced translation and luxation of MC1 in all patients as well as reduced cartilage point loading. Conclusion After DRL reconstruction, luxation of MC1 was reduced in all patients. We quantified movement in both TMC & STT joint, suggesting that pathologies at the TMC joint could lead to compensatory movements at the more proximal joints or vice versa. Simple DRL reconstruction is an attractive alternative for the more invasive anterior oblique ligament reconstruction described by Eaton, serving the same purpose, stabilizing the CMC joint. Future research should investigate if TMC instability and its altered kinematics lead to secondary joint problems (e.g. osteoarthritis) if left unattended.

A virus-evolutionary multi-objective intelligent tool path optimization methodology for 5-axis sculptured surface CNC machining

Sculptured surface machining is a material removal operation essentially adopted to manufacture complex products. Computing optimal tool paths with reference to ideally designed CAD models is indispensable to be able to suggest machining improvements in terms of high quality and productivity. The present paper proposes a new methodology based on a virus-evolutionary genetic algorithm for enhancing sculptured surface tool path planning through an automated selection of values for standard 5-axis end milling strategies' machining parameters to be decided upon in the context of a simulation-based; software-integrated, multi-objective optimization problem. The problem involves surface machining error as the first quality objective represented via the mean value of chordal deviations that tool path interpolation yields and effective radius of inclined tools that affects scallop. Machining time is the second quality objective entering the problem to assess productivity; whereas the number of cutter location points created for each tool path evaluation is also considered. Tool type, tool axis inclination angles as well as longitudinal and transversal steps are considered as the independent parameters in the case of 5-axis machining. Results obtained by conducting evaluation experiments and simulation tests accompanied by an actual machining process provided significant insight concerning the methodology's efficiency and ability of suggesting practically viable results.

The Solar Twin Planet Search

It is still unclear how common the Sun is when compared to other similar stars in regards to some of its physical properties, such as rotation. Considering that gyrochronology relations are widely used today to estimate ages of stars in the main sequence, and that the Sun is used to calibrate it, it is crucial to assess if these procedures are acceptable. We analyze the rotational velocities -- limited by the unknown rotation axis inclination angle -- of an unprecedented large sample of solar twins in order to study the rotational evolution of Sun-like stars, and assess if the Sun is a typical rotator. We use high-resolution ($R = 115000$) spectra obtained with the HARPS spectrograph and ESO's 3.6 m telescope at La Silla Observatory. The projected rotational velocities for 82 solar twins are estimated by line profile fitting with synthetic spectra. Macroturbulence velocities are inferred from a prescription that accurately reflects their dependence with effective temperature and luminosity of the stars. Our sample of solar twins include some spectroscopic binaries with enhanced rotational velocities, and we do not find any non-spectroscopic binaries with unusually high rotation velocities. We verified that the Sun does not have a peculiar rotation, but the solar twins exhibit rotational velocities that depart from the Skumanich relation. The Sun is a regular rotator when compared to solar twins with a similar age. Additionally, we obtain a rotational braking law that better describes the stars in our sample ($v \propto t^{-0.6}$) in contrast to previous, often-used scalings.

工具磨耗抑制を考えた5軸仕上げ加工

It is important to reduce the tool cost in terms of the rationalization of manufacture. On the supposition of 5-axis control machining of metal molds, it is planned to suppress the tool wear by moving the cutting position of ball-end mills. Based on this concept, the experiments are conducted by changing the tool axis inclination direction and the tool swing rate. The tool axis inclination direction is determined at every 45 degrees from the tool feed direction, that is, 8 types. The tool axis inclination angle is selected to be 30 degree from the tool axis in terms of the machined surface roughness with reference to the reported research result. The tool swing rate is appointed by degree per tool feed with the center point of 30 degrees moving from 15 to 45 degrees, taking account of the interference and down-cut operation. As a result, it is confirmed that there exists the appropriate tool axis direction and the tool swing rate, which allow the suppression of tool wear and the realization of good surface roughness.

Some Features of the Surface Micro- and Macroprofile Formation at Flat Face Grinding with Spindle Axis Inclination

The work described in this paper pertains to the identification of some features of micro- and macroprofile formation of surfaces to be machined with flat face grinding, with inclination of the spindle axis. The question of the formation of machined surface profile at through-feed grinding and multiple-pass scheme are considered by using computer-aided simulations in COMPASS environment. More specifically, for flat face through-feed grinding, a generalized empirical equation exhibiting the dependency of concavity from the outer diameter of the face grinding wheel, the spindle axis inclination angle and the width of the surface of the workpiece is acquired. Furthermore, based on the maximum allowable value of flatness deviation and with pre-determined grinding wheel diameter and workpiece width, it is possible to identify the maximum inclination angle at which concavity falls within acceptable limits. For the case of multiple pass flat face grinding, the role of factors such as inclination angle of spindle axis, cross-feed and diameter of the grinding wheel on the height of residual ridges on the surface of the parts is determined through the proposal of an empirical equation. With the aforementioned equations the machinist may reasonably prescribe machining conditions in practice. The conducted research contributes to the expansion of ideas regarding technological possibilities of improvement of flat face grinding.

Surface roughness prediction modelling for commercial dies using ANFIS, ANN and RSM

Surface roughness of dies is considered as a vital quality characteristic. In this study, average surface roughness for a die material H13 has been measured after ball end milling operation. A design of experiment was prepared with response surface methodology (RSM). Forty-nine experiments have been conducted varying six different cutting parameters. This 49 data have been used for training purpose and further 25 testing data have been collected with random selection of input parameters. Better ANFIS model has been selected for minimum value of mean square error, which is constructed with two Gaussian membership functions (gauss2MF) for each input variables and a linear membership function for output. The selected ANFIS model has been compared with theoretical model, ANN and RSM. Comparison shows that the selected ANFIS model gives better result. Correlation test shows that only cutter axis inclination angle and radial depth of cut have positive correlation with surface roughness.

Effects of particle/matrix interface and strengthening mechanisms on the mechanical properties of metal matrix composites

A randomly distributed multi-particle model considering the effects of particle/matrix interface and strengthening mechanisms introduced by the particles has been constructed. Particle shape, distribution, volume fraction and the particles/matrix interface due to the factors including element diffusion were considered in the model. The effects of strengthening mechanisms, caused by the introduction of particles on the mechanical properties of the composites, including grain refinement strengthening, dislocation strengthening and Orowan strengthening, are incorporated. In the model, the particles are assumed to have spheroidal shape, with uniform distribution of the centre, long axis length and inclination angle. The axis ratio follows a right half-normal distribution. Using Monte Carlo method, the location and shape parameters of the spheroids are randomly selected. The particle volume fraction is calculated using the area ratio of the spheroids. Then, the effects of particle/matrix interface and strengthening mechanism on the distribution of Mises stress and equivalent strain and the flow behaviour for the composites are discussed.

Beyond the diffraction limit of optical/IR interferometers

Context. Spectrally resolved long-baseline optical/IR interferometry of rotating stars opens perspectives to investigate their fundamental parameters and the physical mechanisms that govern their interior, photosphere, and circumstellar envelope structures.Aims. Based on the signatures of stellar rotation on observed interferometric wavelength-differential phases, we aim to measure angular diameters, rotation velocities, and orientation of stellar rotation axes.Methods. We used the AMBER focal instrument at ESO-VLTI in its high-spectral resolution mode to record interferometric data on the fast rotator Achernar. Differential phases centered on the hydrogen Br γ line (K band) were obtained during four almost consecutive nights with a continuous Earth-rotation synthesis during ~5 h/night, corresponding to ~60° position angle coverage per baseline. These observations were interpreted with our numerical code dedicated to long-baseline interferometry of rotating stars.Results. By fitting our model to Achernar’s differential phases from AMBER, we could measure its equatorial radius R eq = 11.6 ± 0.3 R ⊙ , equatorial rotation velocity V eq = 298 ± 9 km s-1 , rotation axis inclination angle i = 101.5 ± 5.2°, and rotation axis position angle (from North to East) PArot = 34.9 ± 1.6°. From these parameters and the stellar distance, the equatorial angular diameter ⌀eq of Achernar is found to be 2.45 ± 0.09 mas, which is compatible with previous values derived from the commonly used visibility amplitude. In particular, ⌀eq and PArot measured in this work with VLTI/AMBER are compatible with the values previously obtained with VLTI/VINCI.Conclusions. The present paper, based on real data, demonstrates the super-resolution potential of differential interferometry for measuring sizes, rotation velocities, and orientation of rotating stars in cases where visibility amplitudes are unavailable and/or when the star is partially or poorly resolved. In particular, we showed that differential phases allow the measurement of sizes up to ~4 times smaller than the diffraction-limited angular resolution of the interferometer.

Feed-Interval Scallop Height Estimation Using Multi-axis CNC Milling Machine

This research presents a mathematical model of feed-interval scallop height, where in a machined surface there are two types of scallop height, the pick(path)-interval scallop and the feed-interval scallop. The pick-interval scallop is generated by the finite pick offset between the successive cutting paths, while the feed-interval scallop is generated by the finite increment between the successive tooth feeds. New model that describes and predicts the geometric generating mechanisms of the feed-interval scallop height have been derived using torus cutter which is commonly used in multi-axis milling machine. The machining parameters (effective tool cutter radius, feed per tooth and the magnitude of tool axis inclination angles) have been considered in theoretical and experimental work to study the effect of these parameters on this type of scallop height. From theoretical and experimental work it was found that at high-speed machining, the feed-interval scallop is more important to the surface roughness than the path-interval scallop, and the feed-interval scallop is very sensitive to the tool-axis inclination angle. The feed-interval scallop height decreased sharply and quickly within a few degrees of the tool-axis inclination to the normal workpiece surface. In general, an inclination angle equal to is good enough for all tool diameters used in the present work, namely (6,8,10 12 mm).

Adaptive neuro-fuzzy inference system (ANFIS) based surface roughness prediction model for ball end milling operation

Surface roughness is an index which determines the quality of machined products and is influenced by the cutting parameters. In this study, the average surface roughness Ra(value) for aluminum after ball end milling operation has been measured. 84 experiments have been conducted using varying cutter axis inclination angle (φ degree), spindle speed (S rpm), feed rate (fy mm/min), feed (fx mm), and depth of cut (t mm) in order to find Ra. This data has been divided into two sets on a random basis; 68 training data set and 16 testing data set. The training data set has been used to train different adaptive neuro-fuzzy inference system (ANFIS) models for Ra prediction. And testing data set has been used to validate the models. Better ANFIS model has been selected based on the minimum value of root mean square error (RMSE) which is constructed with three Gaussian membership functions (gaussmf) for each input variables and linear membership function for output. The selected ANFIS model has been compared with theoretical model and response surface model (RSM). This comparison is done based on RMSE and absolute average percentage error. The comparison shows that the selected ANFIS model gives better result for training and testing data. So, this ANFIS model can be used further for predicting surface roughness of aluminum for ball end milling operation. Key words: Ball end mill, adaptive neuro-fuzzy inference system (ANFIS), roughness prediction.

On the alignment of debris discs and their host stars' rotation axis — implications for spin-orbit misalignment in exoplanetary systems

Abstract It has been widely thought that measuring the misalignment angle between the orbital plane of a transiting exoplanet and the spin of its host star was a good discriminator between different migration processes for hot-Jupiters. Specifically, well-aligned hot-Jupiter systems (as measured by the Rossiter–McLaughlin effect) were thought to have formed via migration through interaction with a viscous disc, while misaligned systems were thought to have undergone a more violent dynamical history. These conclusions were based on the assumption that the planet-forming disc was well-aligned with the host star. Recent work by a number of authors has challenged this assumption by proposing mechanisms that act to drive the star–disc interaction out of alignment during the pre-main-sequence phase. We have estimated the stellar rotation axis of a sample of stars which host spatially resolved debris discs. Comparison of our derived stellar rotation axis inclination angles with the geometrically measured debris–disc inclinations shows no evidence for a misalignment between the two.

Progressive Strategy of Milling by means of Tool Axis Inclination Angle

Progressive Strategy of Milling by means of Tool Axis Inclination Angle

Optimum orientation of a torus milling cutter: Method to balance the transversal cutting force

In this paper, a new method for tool positioning in milling on torus cutters with round inserts is presented. A new criterion associated with balancing of the transversal cutting force is used to compute a tool orientation. The considered tool inclination is towards the back of the tool. In this case, all inserts work simultaneously and generate a continuous cutting phenomenon. Each of the inserts produces a transversal cutting force; some being positive while others are negative. A small tool axis inclination angle leads to balancing the transversal cutting force exerted on the tool and then reducing deflection and vibrations in milling operations. Firstly, this approach to the dynamic aspects relating to cutting forces in the milling process is significant for mould and die manufacturing since it allows polishing time to be reduced. In addition, as vibrations are reduced, enhanced surface quality can be obtained directly on free-form surfaces such as aeronautic fittings.

High-Resolution Spectroscopy of NGC 7026

Up to now, the geometrical and kinematical structure of the well-known bizarre nebula NGC 7026 has not been discussed in the literature. Using the large vertical Coude spectrograph of the 2.2 m telescope on Calar Alto, Spain, we obtained long-slit spectra covering the nebula at 5 different position angles, in the ranges from 4730 to 5050 Å and from 6470 to 6770 Å. The high spectral (up to 6 km s−1 FWHM) and spatial resolution (seeing-limited ≲ 2″) reveals a rather complex structure in the lines of Hα, Hβ, (OIII) λλ 4959, 5007, HeI 6678, HeII 6560, (NII) λλ 6548, 6583, and (SII) λλ 6716, 6731. Generally, the lines exhibit a double “bowed” appearance; both components consist of several condensations of small angular extent. The velocity field suggests a non-spherical expansion of an elongated thin shell structure. The observations can be explained by an ovoidal or “bipolar” configuration of the nebula consisting of an expanding equatorial toroid (Vexp = 54 km s−1 in (SII)) and two blobs moving at higher velocities outwards along the polar axis (inclination angle with respect to the line-of-sight: 75°). The geometrical and kinematical structure observed in the lines of various excitation degrees indicates a pronounced ionization stratification and allows to derive the dependence of the expansion velocities on the radial distance inside the nebulae. No noticeable extinction within the nebula has been found. The bipolar structure of NGC 7026 resembles that of some other planetary nebulae and might be caused by an equatorial concentration of the circumstellar material lost during the late phase by the progenitor asymptotic giant-branch star. Using distances and interstellar extinctions of 48 stars within 1° of the planetary, we determined a distance of 2180 (≈ ± 700) pc for the nebula.

The angle of inclination of the sunspot symmetry axis to the solar surface

The Wilson effect, used before only as a method of determining the physical depression of sunspots, is used here to estimate a quite different parameter - the sunspot symmetry axis inclination angle to the solar surface, this explains the observed negative Wilson effect. On the basis of photoheliograms taken with three telescopes of the High-Altitude Solar observatory ‘Peak Alma-Ata’, the Wilson effect for the whole solar disk is investigated, the east and west parts of the disk being studied separately. 111 sunspots of regular shape at different heliocentric angles were measured, eight of them being under observations from one limb to the other. To study the dependence of the Wilson effect on the heliocentric angle, all observations within an angular interval of 10° were averaged. The dependence thus derived is described by two sinusoids having the zero point shifted along both axes. The shift of the zero Wilson effect to the west, i.e., a shift along the heliocentric angle axis, can be caused by the deviation of the sunspot axis to the east from the normal to the solar surface. On the ‘line of sight-normal’ plane the angle corresponding to this deviation is ψ=34°±14°.

An exploratory study of the roll behavior of ablating cones

and d) are zero at roll rate. 3) Small trim angles of attack (fr < 0.25°), which can be produced by principal axis inclination angles of similar magnitude, may seriously degrade the performance of re-entry vehicles that have mass asymmetries. 4) Effects of inertia asymmetries on the angular and rolling motions of ballistic re-entry vehicles may be misinterpreted as the effects of mass and aerodynamic asymmetries.