Low Wheel Speed Research Articles

Effects of a New Type of Grinding Wheel with Multi-Granular Abrasive Grains on Surface Topography Properties after Grinding of Inconel 625.

Finishing operations are one of the most challenging tasks during a manufacturing process, and are responsible for achieving dimensional accuracy of the manufactured parts and the desired surface topography properties. One of the most advanced finishing technologies is grinding. However, typical grinding processes have limitations in the acquired surface topography properties, especially in finishing difficult to cut materials such as Inconel 625. To overcome this limitation, a new type of grinding wheel is proposed. The tool is made up of grains of different sizes, which results in less damage to the work surface and an enhancement in the manufacturing process. In this article, the results of an experimental study of the surface grinding process of Inconel 625 with single-granular and multi-granular wheels are presented. The influence of various input parameters on the roughness parameter (Sa) and surface topography was investigated. Statistical models of the grinding process were developed based on our research. Studies showed that with an increase in the cutting speed, the surface roughness values of the machined samples decreased (Sa = 0.9 μm for a Vc of 33 m/s for a multigranular wheel). Observation of the grinding process showed an unfavorable effect of a low grinding wheel speed on the machined surface. For both conventional and multigranular wheels, the highest value for the Sa parameter was obtained for Vc = 13 m/s. Regarding the surface topography, the observed surfaces did not show defects over large areas in the cases of both wheels. However, a smaller portion of single traces of active abrasive grains was observed in the case of the multi-granular wheel, indicating that this tool performs better finishing operations.

Shifting Process Optimization of Dedicated Hybrid Transmission

The shifting process of a hybrid electric vehicle (HEV) could be implemented by a motor to simplify the control requirement when the clutch is engaged. In order to reduce the vehicle jerk and simplify the clutch control requirement during the shifting process, this paper introduces a 3-speed dedicated hybrid transmission (3DHT) with P1/P3 configuration and a power shift control strategy. A finite-time linear quadratic regulator (LQR) is proposed to smoothly transfer torque and suppress driveline oscillations during the torque transfer process with a maximum jerk of 5.6 m/s³. Since the clutch stays engaged, a predictive sliding mode control (SMC) is proposed to track the speed of the sleeve quickly and precisely during the synchronization process, which takes 0.18s and maintains a speed difference of around 1 rpm. Furthermore, a Kalman Filter is utilized to overcome the difficulties associated with side shaft torque measurement and low wheel speed resolution. A simulation is performed in MATLAB/SIMULINK, and the powershift (2nd -> 3rd) is compared with other methods. The comparison indicates that the proposed power shift strategy can reduce the maximum jerk from 14.8 m/s3 to 5.6 m/s3, while the entire shifting process lasts for 0.71s. Therefore, the proposed power shift control strategy effectively improves the shift quality.

Analysis of cutting forces during grinding of titanium alloy and corrosion-resistant steel by diamond, electrocorundum and cubic borine nitrid wheels

The object of research is the process of circular and surface grinding of titanium alloy and corrosion-resistant steel, namely, the cutting forces arising from mechanical processing. One of the most problematic areas in work is the selection of the required grinding modes, material and grinding wheel grain size. In the course of the experiment, we used samples of VT8 titanium alloy and 12Х18N9T steel, on which the grinding process was studied with wheels made of various materials (electrocorundum, cubic boron nitride (CBN), diamond). The values of the cutting forces Py and Pz were obtained in the latitude of permissible modes, which are most often used in circular and flat grinding, and can reach maximum values, respectively, Py=27 N, Pz=15.5 N. The data were obtained at a low wheel speed from electrocorundum, about 15 m/s and grain size 8. By reducing the grain size of the wheel, we get the effect of increasing the energy consumption of the grinding process, due to the increase in the values of the cutting forces. If we compare the cutting forces arising from grinding with different wheels, then the following can be noted. Compared to electrocorundum wheels, when using CBN wheels, the cutting forces are reduced by 20–25 %, and when grinding with diamond wheels (despite the high wear of the diamond wheel), the effect of cutting forces is reduced by 25–30 %. This is due to the fact that cutting conditions are the most favorable for diamond and CBN grains, which makes it possible to use more intense cutting conditions. The results of the study allow predicting the performance of the grinding wheel, reducing the energy consumption of production, and also adjusting the processing mode of the part to obtain the necessary quality indicators of the surface layer and the geometric dimensions of the part.

Feasibility study of creep feed grinding of 300M steel with zirconium corundum wheel

The ultrahigh strength 300M steel has been commonly used in the manufacture of aircraft landing gear and rotor shaft parts due to its excellent mechanical properties. Creep feed grinding is one of the essential operations during the whole component manufacturing processes. In this work, the feasibility of creep feed grinding of 300M steel by using the hard zirconium corundum wheel was theoretically and experimentally evaluated. A variety of responses including grinding forces, temperature fields, specific grinding energy, surface integrity and chip modes were carefully recorded. Besides, the mechanism of ground surface profile generation and the spatial frequency spectrum of the surface profile were tentatively analyzed. It was found that the wheel speed has a relative influence on the grinding forces and temperatures of which the work hardening effect dominates the material removal with lower wheel speed while the thermal softening becomes crucial as the wheel speed exceeds the critical value for the studied 300M steel. Furthermore, a scattered spatial frequency spectrum for the generated surface profile was noticed with lower wheel speed while the spectrum gathers towards the lower frequency values with higher amplitude as the wheel speed increases. The shearing chip and flowing chip dominates the main chip type, indicating the excellent abrasive sharpness during the grinding process. In general, the used zirconium corundum wheel presents feasibility for the creep feed grinding of 300M steel because of the high material removal rate, absence of surface burn, low wheel wear and higher compressive residual stresses.

Experimental and theoretical investigation into surface roughness and residual stress in magnetorheological finishing of OFHC copper

Highly finished copper surface without any appreciable residual stress is in high demand in electronics, space, and optical industries. Conventional finishing processes are not suitable for the finishing of copper owing to its extremely lower hardness. In the present study, wheel based magnetorheological finishing (MRF) process is used to attain nanolevel surface roughness of oxygen-free high conductivity (OFHC) copper. The wheel speed, working gap and feed rate are selected as the main controlling process parameters. Areal surface roughness ( S a ), normal force, tangential force and residual stress are studied as the response parameters. The measurement of residual stress has a significant importance as it may affect the optical properties of the finished surface. The residual stresses and phases of all the finished surfaces are analysed using X-ray diffraction (XRD) technique. A theoretical model is proposed to predict the surface roughness of the MRF processed surfaces. It is observed that a nanolevel surface roughness with lower residual stress can be attained by performing MRF with a higher working gap, and lower wheel speed and feed rate. In the present study, a minimum surface roughness ( S a ) of 15.5 nm and compressive residual stress of 6.9 MPa are attained on the OFHC copper surface.

Multiple origins of anomalous eutectic microstructure in rapidly solidified Mg-Al alloy

Mg-33.3 wt.%Al eutectic alloys were fabricated by melt spinning at wheel speeds from 5 to 50 ms−1. SEM and S/TEM analyses showed the formation of anomalous eutectic structures at all wheel speeds. Four distinctive eutectic microstructures were observed, depending on the wheel speed, each with a unique formation mechanism. At low wheel speeds, solute trapping and high interfacial energy resulted in the remelting of primarily grown regular eutectic microstructures and was responsible for the formation of the anomalous eutectic Type A. A coupled-to-decoupled-growth transition occurred at intermediate wheel speeds giving rise to the anomalous eutectic Type B. The decoupled nucleation and growth of the eutectic phases followed by a coupled dendritic growth lead to the formation of flower-like microstructures at anomalous eutectic Type C. At sufficiently high wheel speed, no sign of regular eutectic was found and a unique cellular microstructure of ϒ phase along with inter- or intragranular α phase grains was formed, anomalous eutectic Type D, as a result of the decoupled nucleation and growth of the eutectic phases. The observed microstructures were examined thoroughly, and the correlated formation mechanisms were discussed on the basis of the SEM images and S/TEM and EDS analysis.

A DEM approach to assess the influence of the paddle wheel shape on force feeding during pharmaceutical tableting

Pharmaceutical tablet quality is tightly controlled to ensure the patient’s safety. Though the tableting process is a well-known and accepted approach, process understanding is frequently built upon long-time experience of the operators. This is also true for the first step in tableting, the die filling where the powder is fed from the hopper through a force feeding system into the rotating dies of the turret. The current study considers a three-chambered force feeder of a FETTE 1200i, with the focus to evaluate the influence of the paddle wheel shape, which may either be of cylindrical or cuboid shaped blades, on tablet quality. A numerical approach utilizing the discrete element method allowed to compute the powder transfer in the tablet press which helps in identifying the optimal paddle wheel shape configuration. For instance, at a low turret – high paddle wheel speed, the cylindrical configuration revealed highest quality with respect to tablet mass, tablet mass variation, and content uniformity. In contrast, the cuboid configuration indicated better quality at a high turret – low paddle wheel speed. In addition, the detailed analysis of macroscopic and microscopic powder flow phenomena within the force feeder was performed which improves general process understanding in pharmaceutical development.

Stability analysis for SiC grinding based upon harmonic wavelet and Lipschitz exponent

In order to effectively identify the stability degree of grinding and obtain better surface integrity of machined workpiece in grinding application, in this paper, a quantitative assessment approach based on harmonic wavelet and Lipschitz exponent is proposed, using silicon carbide as an example. To begin with, the Lipschitz exponent is defined and calculated by harmonic wavelet modulus maxima (HWMM) and linear regression algorithm, respectively. Then the Kurtosis based on Lipschitz exponent (KLE) is defined as a quantitative indicator. In grinding experiment, the acceleration signals and grinding force signals of the X/Y directions are selected, and experimental parameters including wheel speed, workpiece speed and grinding depth are employed to investigate the grinding stability in grinding stage. Experimental results show that the grinding stability is relatively worse at low wheel speed, low-high workpiece speed and large grinding depth in terms of KLE index, which may provide a new guidance to explore optimized grinding parameters and thus obtain good surface integrity in engineering applications.

Hard Magnetic Property Improvement of Melt-Spun PrCo5 Ribbons by Fe and C Doping

Magnetic properties and microstructure of melt-spun PrCo5− x − y Fe x C y ( x = 0 and 0.3; y = 0–0.3) ribbons are studied. For PrCo5 ribbons spun at lower wheel speed of 20 m/s, the coexistence of 2:17 phase with magnetic hard 1:5 phase leads to low coercivity of 0.6 kOe. Increasing wheel speed to 40 m/s imroves the coercivity to 3.3 kOe due to the increased volume fraction of 1:5 phase. Interestingly, magnetic properties of PrCo5 ribbons melt spun at 40 m/s ( Br = 6.4 kG, i H c = 3.3 kOe, and ( BH )max = 4.5 MGOe) are improved to Br = 6.1–6.5 kG, i H c = 7.8–13.5 kOe, ( BH )max = 7.3–8.9 MGOe by doping C, and significantly enhanced to Br = 6.3 kG, i H c = 16.1 kOe, and ( BH )max = 9.3 MGOe for C and Fe co-doped PrCo4.6Fe0.3C0.1 ribbons. The structural and thermo-magnetic analysis confirms that the entrance of Fe and part of C into the crystal structure of 1:5 phase leads to the increase of Curie temperature. Doping proper C content not only uniformly refines grain size and, therefore, improves the squareness of demagnetization curve and ( BH )max, but also increases the volume fraction of 1:5 phase, and thus enhances the coercivity. The increased volume fraction of 1:5 phase and the reduced magnetic domain size due to refined microstructure by co-doping Fe and C make PrCo4.6Fe0.3C0.1 ribbons exhibit a high permanent magnetic performance. They are promising candidate materials for making bonded magnets.

Helium ions irradiation-induced surface damage in Fe-based melt-spun ribbons

The Fe78Si8B14 and Fe78P8B14 ribbons with different wheel speeds were prepared by melt-spinning, and their responses to He+ ion irradiation were investigated. Previous studies had shown that the ion beam resistance capability of amorphous ribbons was better than their corresponding crystalline counterparts. However, no significant changes on the surface at low fluence are observed. At a relatively higher fluence, both the ribbons prepared at low and high wheel speeds behave the similar irradiation responses: peeling, flaking and multi-layer damages occur. The fully amorphous ribbons prepared at a high wheel speed can accommodate partial incident ions owing to the inherent disordered structure. As the irradiation fluence increases, they fail to accommodate the excess incident ions, which easily aggregate to result in the surface damage. While the partial amorphous ribbons prepared at a low wheel speed possess lots of unstable crystalline grain boundaries owing to the precipitation of Si- or P-rich phase, which may act as the source for the irradiation-induced defects annihilation. Results show that the size and the fraction of precipitate phases in amorphous matrix may play a dominated role in resisting the ion irradiation.

Effect of wheel speed on magnetic and mechanical properties of melt spun Fe-6.5 wt.% Si high silicon steel

Fe-Si electric steel is the most widely used soft magnetic material in electric machines and transformers. Increasing the silicon content from 3.2 wt.% to 6.5 wt.% brings about large improvement in the magnetic and electrical properties. However, 6.5 wt.% silicon steel is inherited with brittleness owing to the formation of B2 and D03 ordered phase. To obtain ductility in Fe-6.5wt.% silicon steel, the ordered phase has to be bypassed with methods like rapid cooling. In present paper, the effect of cooling rate on magnetic and mechanical properties of Fe-6.5wt.% silicon steel is studied by tuning the wheel speed during melt spinning process. The cooling rate significantly alters the ordering and microstructure, and thus the mechanical and magnetic properties. X-ray diffraction data shows that D03 ordering was fully suppressed at high wheel speeds but starts to nucleate at 10m/s and below, which correlates with the increase of Young’s modulus towards low wheel speeds as tested by nanoindentation. The grain sizes of the ribbons on the wheel side decrease with increasing wheel speeds, ranging from ∼100 μm at 1m/s to ∼8 μm at 30m/s, which lead to changes in coercivity.

Evaluation of Surface Mechanical Properties and Grindability of Binary Ti Alloys Containing 5 wt % Al, Cr, Sn, and V

This study aimed to investigate the relationship between the surface mechanical properties and the grindability of Ti alloys. Binary Ti alloys containing 5 wt % concentrations of Al, Cr, Sn, or V were prepared using a vacuum arc melting furnace, and their surface properties and grindability were compared to those of commercially pure Ti (cp-Ti). Ti alloys containing Al and Sn had microstructures that consisted of only α phase, while Ti alloys containing Cr and V had lamellar microstructures that consisted of α + β phases. The Vickers microhardness of Ti alloys was increased compared to those of cp-Ti by the solid solution strengthening effect. Among Ti alloys, Ti alloy containing Al had the highest Vickers microhardness. At a low SiC wheel speed of 5000 rpm, the grinding rates of Ti alloys showed an increasing tendency as the hardness values of Ti alloys decreased. At a high SiC wheel speed of 10,000 rpm, the grinding rates of Ti alloys showed an increasing tendency as the tensile strength values increased. The Ti alloy containing Al, which showed the lowest tensile strength, had the lowest grinding rate. The grinding ratios of the Ti alloys were higher than those of cp-Ti at both wheel revolution speeds of 5000 and 10,000 rpm. The grinding ratio of the Ti alloy containing Al was significantly increased at 10,000 rpm (p < 0.05).

Effect of quenching rate on the microstructure and mechanical behavior of Ce75Al21Ga4 glassy alloy

The present study deals with the structural and microstructural changes with respect to the quenching rate and their correlation with mechanical behavior of melt-spun Ce75Al21Ga4 glassy alloys. The ribbons of the alloy have been synthesized at different quenching rates obtained through different wheel speeds (44, 36, 29, 22 and 15m/s). The glass forming indicators and mechanical properties have been investigated at different quenching rates. The higher quenching rate obtained through high wheel speed (44, 36 and 29m/s) has led to phase separation giving rise to nano-amorphous domains in a glassy matrix while the lower quenching rate obtained through lower wheel speed (22 and 15m/s) produces nano-crystalline grains with size ranges from 25±1 to 120±1nm. It has been found that the size of the nano-amorphous domains decreases with decrease in wheel speed. The mechanical behavior has been studied using micro-indentation technique. The indentation test indicates that with the same chemical composition, the ribbons synthesized at slow quenching rate exhibits higher hardness and yield strength than those synthesized at faster quenching rate. The ribbons synthesized at 44m/s contains the large free volume and has the highest shear band density.

Aerodynamic design of an ultra-highly loaded booster of a high bypass ratio turbofan

Based on an existing high bypass ratio turbofan, this paper uses a new concept of diffusion blade profiles with large camber and low flow losses to design a rotor for the booster, which characterizes the low wheel speed, thus achieving ultra-high loading of the rotor, effectively increasing its stage pressure ratio and reducing the weight of the booster. A booster with only one stage is designed by using the new blade profiles to replace the original booster with three stages. A two-dimensional design method of S1 (blade to blade)/S2 (hub to tip) stream surfaces is applied to design the blades of the rotor and the stator in the booster, and the two-dimensional blade profiles in the S1 stream surface are designed by means of an optimization design method. The flow fields in the original and newly designed boosters are simulated by using a numerical method. At the design point, the newly designed booster has nearly the same total pressure ratio and mass flow rate as the original booster and exhibits higher efficiency than the original booster. The surge margins of both boosters are nearly equal, and the newly designed booster can preferably match the original intermediate case.

Phase precipitation behavior of rapidly quenched ternary La–Fe–B alloy and the effects of Nd substitution

To understand the structure and phase precipitation behavior of the ternary La–Fe–B alloy, the effects of wheel speed and heat treatment on the melt spun La2Fe14B alloy were investigated. The results show that the hard magnetic La2Fe14B (2:14:1) phase is difficult to obtain in the ternary alloy. The α-Fe and La phases mainly precipitated as spun ribbons prepared at relatively low wheel speeds, and a more amorphous phase formed at higher wheel speeds. With the annealing temperature increasing from 400 °C to 500 °C and 800 °C, the α-Fe and La phases also gradually precipitated from the amorphous matrix. A liquid La-rich phase and α-Fe phase could coexist in the alloy at high temperature. However, the substitution of Nd for La can greatly enhance the formation of a hard 2:14:1 phase. The effects of Nd substitution on the structure and phase precipitation during annealing for the (La1−xNdx)2Fe14B (x = 0.1. 0.2, 0.3 and 0.4) alloys have been also investigated. The present results are important for exploring high-performance low-cost La-based Nd–Fe–B magnets.

Experimental analysis of contact fatigue damage in case hardened gears for off-highway axles

Abstract Pitting is one of the main causes of failure in planetary gear sets of axles designed for agricultural vehicles. The high torque and the low wheel speed typical of such machines result in poor lubrication and promote the onset of contact fatigue failure by pitting, which generally occurs earlier in the sun gear than in both the planets and the ring of wheel hub planetary drives. In fact, sun gears are subjected to the highest contact pressure and, at the same time, unfavourable rolling-sliding working conditions. In this paper, six case hardened sun gears damaged by pitting during endurance tests were analysed. The aim of the analysis was to highlight the key aspects of the morphology and the evolution of pitting damage on the case hardened sun gears.

Hydrogenation properties of as quenched Ti45Zr38Ni17quasicrystalline alloys

The present study deals with the microstructural changes with respect to the processing parameter (quenching rate) and their correlation with hydrogen storage characteristics of Ti45Zr38Ni17 quasicrystalline alloys. The ribbons of the alloy have been synthesized at different quenching rates obtained through different wheel speeds (35, 40, 45 and 50 m/s) and investigated for their hydrogen storage characteristics. The lower cooling rate obtained through low wheel speed (35 m/s) produces, i-phase grains whose size ranges from 300- 350 nm, whereas higher cooling rates obtained through high wheel speed (45 and 50 m/s) promote the formation of grains with size ranges from 100-150 nm in Ti45Zr38Ni17 ribbons. It has been found that the ribbons synthesized at 35 m/s absorbed ∼2.0 wt%, whereas ribbons synthesized at 50 m/s absorbed ∼2.84 wt. % of hydrogen. Thus the hydrogen storage capacity of ribbon increases for the ribbons produced at higher quenching rate. One of the salient features of the present study is that the improvement of hydrogen storage capacity obtained through higher quenching rates (∼45 to 50 m/s wheel speed) leading to the formation of lower grain size.

Role of Si on structure and soft magnetic properties of Fe87−xSixB9Nb3Cu1 ribbons

Abstract Role of Si content on the structural, thermal and soft magnetic properties of melt spun and annealed Fe 87− x Si x B 9 Nb 3 Cu 1 ( x = 11, 13, 18, 20, 25 and 30 at.%) alloys has been investigated. Processing of ribbons at a higher wheel speed (47 m/s) during melt spinning results in the formation of amorphous phase in all the alloys expect for 30 at.% Si whereas at lower wheel speed (34 m/s), amorphous phase has been observed only in 18 at.% Si alloy ribbon. Detailed thermal analyses revealed that higher glass forming ability of 18 at.% Si alloy is due to the near eutectic point in these alloy series and higher ratio between the crystallization and liquidus temperature ( T x / T L ). On annealing, nanocrystalline Fe 3 Si phase was found to be precipitated out in amorphous matrix in alloys up to 20 at.% Si ribbons whereas paramagnetic Fe 4.9 Si 2 B phase along with Fe 3 Si phase was observed in 25% Si ribbon. Detailed Mossbauer spectroscopy of the annealed ribbons revealed that the composition of the nanocrystalline Fe 3 Si phase increases from Fe-21 at.% Si towards the stoichiometric composition (Fe-25 at.% Si) with Si content. The results are also corroborated with precision lattice parameter measurements. The coercivity of the annealed ribbons initially decreases, attains a minimum at 18 at.% Si and then increases abruptly with Si content.

Effects of Cr3C2 content and wheel speed on amorphization behavior of melt-spun SmCo7-x(Cr3C2)x alloys

The effects of the Cr3C2 content and wheel speed on the amorphization behavior of the melt-spun SmCo7-x(Cr3C2)x (x=0.10-0.25) alloys were studied systematically by X-ray diffraction analysis (XRD), differential scanning calorimetry (DSC) and magnetic measurements. The ribbon melt-spun at lower wheel speed (20 m/s) has composite structure composed of mostly SmCo7 and a small amount of Sm2Co17R. The grain size of SmCo7 phase decreases with the increase of Cr3C2 content. With the increase of wheel speed, the XRD peaks become lower and accompanied with a broad increase in backgrounds, indicating a considerable decrease in the grain size of the SmCo7 phase. When the wheel speed increases to 40 m/s, SmCo7-x(Cr3C2)x alloys can be obtained in the amorphous state for 0.15≤x≤0.25 with intrinsic coercive Hci of 0.004-0.007 T. The DSC analysis reveals that SmCo7 phase firstly precipitates from the amorphous matrix at 650 °C, followed by the crystallization of Sm2Co17 phase at 770 °C.

Corrosion Behavior and Surface Analysis of Melt-Spun Mg-Based Metallic Glass in Physiological Saline Solution

The developed Mg-based metallic glass shows great potential as implants in biomedical applications instead of crystalline Mg alloys, which may possesses acceptable corrosion properties. In this study, corrosion behaviors of melt-spun amorphous Mg67Zn28Ca5 ribbons were investigated in physiological saline solution. Electrochemical testing and hydrogen evolution rate indicated that the glassy ribbons obtained at lower wheel speed were more noble with smaller corrosion current, and possessed a comparatively lower corrosion rate in physiological saline solution. Surface morphology analysis revealed that glassy Mg67Zn28Ca5 ribbons exhibited a strong susceptibility to localized pitting corrosion. A Zn-rich passive layer was formed on the surfaces of the glassy ribbons, indicating that Zn was an effective alloying element to enhance the corrosion resistance of amorphous Mg67Zn28Ca5 alloys.