一种实用型动平衡去材料设备

航空产品往往通过去材料(即减材料法)实现动平衡,某公司生产的多种轴类零件在进行动平衡去材料时要求去材料处形状有严格的圆周角度、位置、深度、圆弧大小以及粗糙度等。以往使用气动风枪,采用手工打磨造成去材料处形状不规范、不圆滑、深度不一、粗糙度差且易造成烧伤等,给产品质量带来极大安全隐患,为此设计制造了一种简易动平衡去材料设备。此设备具有结构简单、操作方便、应用范围广、容易制造等优点。目前该设备已广泛运用在各种轴类、薄壁管等零件的动平衡去材料工步中,效果好。

NOVEL METHOD FOR DYNAMIC OPTIMIZATION OF STABILITY IN HIGH-SPEED MILLING SYSTEM

Considering the self-excited and forced vibrations in high-speed milling processes, a novel method for dynamic optimization of system stability is used to determine the cutting parameters and structural parameters by increasing the chatter free material removal rate （CF-MRR） and surface finish. The method is hased on the theory of the chatter stability and the semi-bandwidth of the resonant region. The objective function of the method is material removal rate（MRR）,the constraints are chatter stability and surface finish, and the optimizing variables are cutting and structural parameters. The optimization procedure is stated. The method is applied to a milling system and CF-MRR is increased 18.86%. It is shown that the influences of the chatter stability and the resonance are simultaneously considered in the dynamic optimization of the milling system for increasing CF-MRR and the surface finish.

Optimization of micro milling electrical discharge machining of Inconel 718 by Grey-Taguchi method

The optimization of micro milling electrical discharge machining（EDM） process parameters of Inconel 718 alloy to achieve multiple performance characteristics such as low electrode wear,high material removal rate and low working gap was investigated by the Grey-Taguchi method.The influences of peak current,pulse on-time,pulse off-time and spark gap on electrode wear（EW）,material removal rate（MRR） and working gap（WG） in the micro milling electrical discharge machining of Inconel 718 were analyzed.The experimental results show that the electrode wear decreases from 5.6×10-9 to 5.2×10-9 mm3/min,the material removal rate increases from 0.47×10-8 to 1.68×10-8 mm3/min,and the working gap decreases from 1.27 to 1.19 μm under optimal micro milling electrical discharge machining process parameters.Hence,it is clearly shown that multiple performance characteristics can be improved by using the Grey-Taguchi method.

IMPROVING MATERIAL REMOVAL RATE OF BRITTLE CERAMICS THROUGH HONING INCIDENTAL TENSILE STRESSES

The stress intensity factors and stress conditions of machining cracks are analyzed by fracture mechanics on the basis of honing characteristics and of brittle ceramic mechanical behavior.Because the honing incidental tensile stresses effectively decrease the critical grinding stresses and increase the stress intensity factors of machining cracks,the honing process can be carried out easily.The results show that honing can be an efficient machining method for brittle materials.

Prediction Model for Net Cutting Specific Energy in CNC Turning

A prediction model for net cutting specific energy in computer numerical control(CNC)turning based on turning parameters and tool wear is developed.The model can predict the net cutting energy consumption before turning.The prediction accuracy of the model is verified in AISI 1045 steel turning.The comparative experimental results show that the prediction accuracy of the model is significantly improved because the influence of tool wear is taken into account.Finally,the influences of turning parameters and tool wear on net cutting specific energy are studied.With the increase of cutting depth,the net cutting specific energy decreases.With the increase of spindle speed,the additional load loss power of spindle drive system increases,so the net cutting specific energy increases.The net cutting specific energy increases approximately linearly with tool wear.The results are helpful to formulate efficient and energy-saving CNC turning schemes and realize low‑carbon manufacturing.

Electrical discharge machining of 6061 aluminium alloy

The wire electrical discharge machining（EDM） of 6061 aluminium alloy in terms of material removal rate,kerf/slit width,surface finish and wear of electrode wire for different pulse on time and wire tension was studied.Eight experiments were carried out in a wire EDM machine by varying pulse on time and wire tension.It is found that the material removal rate increases with the increase of pulse on time though the wire tension does not affect the material removal rate.It seems that the higher wire tension facilitates steady machining process,which generates low wear in wire electrode and better surface finish.The surface roughness does not change notably with the variation of pulse on time.The appearance of the machined surfaces is very similar under all the machining conditions.The machined surface contains solidified molten material,splash of materials and blisters.The increase of the pulse on time increases the wear of wire electrode due to the increase of heat input.The wear of wire electrode generates tapered slot which has higher kerf width at top side than that at bottom side.The higher electrode wear introduces higher taper.

Design of a device for precision shaping of grinding wheel macro-and micro-geometry

The selected modifications to the construction of grinding wheels were described which facilitate an increase in the material removal rate （grinding wheels with conic chamfer and grinding wheels with microdiscontinuities on the active surface）. Using these background details, a suggested thesis was put forward regarding the need to develop a device which will allow for the shaping of the macrogeometry of the grinding wheel （cylindrical and conical surfaces） and the microdiscontinuities within the dressing operation simultaneously. The device was presented and prepared in two functional variants （horizontal and vertical mounting of the motor）, then a prototype was described. An example of the grinding wheel active surface, shaped by using this device, was also presented. The theoretical analysis and experimental verification performed determine that the error of shaping the conic chamfer angle within the range of 0-1.5°, using the developed device, is approximately ±3%.

Removal of Cd（II） by Nanometer AIO（OH） Loaded on Fiberglass with Activated Carbon Fiber Felt as Carrier

A new nanometer material, nanometer AlO（OH） loaded on the fiberglass with activated carbon fibers felt（ACF） as the carrier, was prepared by hydrolytic reaction for the removal of Cd（II） from aqueous solution using column adsorption experiment. As was confirmed by XRD determination, the hydrolysis production loaded on fiberglass was similar to the orthorhombic phase AlO（OH）. SEM images showed that AlO（OH） particles were in the form of small aggregated clusters. The Thomas model was applied for estimating the kinetic parameters and the saturated adsorption ability of Cd（II） adsorption on the new adsorbent. The results showed that the maximum adsorption capacity of Cd（II） was 128.50 mg·g^-1 and 117.86 mg·g^-1 for the adsorbent mass of 0.3289 g and the adsorbent mass of 0.2867 g, respectively. The elution experiment result indicated that the adsorbed Cd ions was easily desorbed from the material with 0.1 mol·L^-1 HCl solution. Adsorption-desorption cycles showed the feasibility of repealed uses of the composited material. The adsorption capacities were influenced by pH and the initial Cd（II） concentration. The amount adsorbed was greatest at pH 6.5 and the initial Cd（II） concentration of 0.07 mg·L^-1, respectively. Nanometer AlO（OH） played a major role in the adsorption process, whereas the fiberglass and ACF were assistants in the process of removing Cd（II）. In addition, the adsorption capacities for Cd（II） were obviously reduced from 128.50 mg·L^-1 to 64.28 mg·L^-1 when Pb ions were present because Pb ions took up more adsorption sites.

Deep purification of As(V)in drinking water by silica gel loaded with FeOOH and MnO_(2)

For deep purification of As(V)from drinking water by adsorption,two adsorbents S-FeOOH and S-MnO_(2) were successfully synthesized by loading FeOOH and MnO_(2) nanoparticles onto silica gel in situ.Characterization of the adsorbents implied that S-FeOOH and S-MnO_(2) with large particle size(diameter of 150−250μm)still had high specific surface areas(357.0 and 334.6 m^(2)/g)due to their specific amorphous and porous structure.In batch experiments,the influences of pH,contact time,adsorbent dosage,and temperature on the adsorption were investigated.Comparing with other adsorbents reported,the synthesized adsorbents in this study,especially S-FeOOH,showed good performance for As(V)removal in a wide pH(2−12)and temperature(25−65℃)range.The residual As(V)concentration after S-FeOOH treatment was around 0.01 mg/L,which met the drinking water standard.The adsorption process followed the pseudo-second-order kinetic model,and the adsorption equilibrium was reached within 5 min.The equilibrium adsorption data of S-FeOOH can be well fitted by the Langmuir isotherm,while that of S-MnO_(2) followed Freundlich model,which indicated their different adsorption mechanisms.The results show that S-FeOOH is superior to S-MnO_(2) in eliminating As(V),and S-FeOOH could be used as a promising adsorbent for the deep purification of As(V)in drinking water.

Electrolyte composition and removal mechanism of Cu electrochemical mechanical polishing

The optimization of electrolytes and the material removal mechanisms for Cu electrochemical mechanical planarization(ECMP)at different pH values including 5-methyl-1H-benzotriazole(TTA),hydroxyethylidenediphosphoric acid(HEDP),and tribasic ammonium citrate(TAC)were investigated by electrochemical techniques,X-ray photoelectron spectrometer(XPS)analysis,nano-scratch tests,AFM measurements,and polishing of Cu-coated blanket wafers.The experimental results show that the planarization efficiency and the surface quality after ECMP obtained in alkali-based solutions are superior to that in acidic-based solutions,especially at pH=8.The optimal electrolyte compositions(mass fraction)are 6% HEDP,0.3% TTA and 3% TAC at pH=8.The main factor affecting the thickness of the oxide layer formed during ECMP process is the applied potential.The soft layer formation is a major mechanism for electrochemical enhanced mechanical abrasion.The surface topography evolution before and after electrochemical polishing(ECP)illustrates the mechanism of mechanical abrasion accelerating electrochemical dissolution,that is,the residual stress caused by the mechanical wear enhances the electrochemical dissolution rate.This understanding is beneficial for optimization of ECMP processes.

Application and mechanism of Fenton-like iron-based functional materials for arsenite removal

Between the two major arsenic-containing salts in natural water, arsenite(As(Ⅲ)) is far more harmful to human and the environment than arsenate(As(V)) due to its high toxicity and transportability. Therefore, preoxidation of As(Ⅲ) to As(V) is considered to be an effective means to reduce the toxicity of arsenic and to promote the removal efficiency of arsenic. Due to their high catalytic activity and arsenic affinity, iron-based functional materials can quickly oxidize As(Ⅲ) to As(V) in heterogeneous Fenton-like systems, and then remove As(V) from water through adsorption and surface coprecipitation. In this review, the effects of different iron-based functional materials such as zero-valent iron and iron(hydroxy) oxides on arsenic removal are compared, and the catalytic oxidation mechanism of As(Ⅲ) in heterogeneous Fenton process is further clarified. Finally, the main challenges and opportunities faced by iron-based As(Ⅲ) oxidation functional materials are prospected.

Defect-free surface of quartz glass polished in elastic mode by chemical impact reaction

Removal of brittle materials in the brittle or ductile mode inevitably causes damaged or strained surface layers containing cracks, scratches or dislocations. Within elastic deformation, the arrangement of each atom can be recovered back to its original position without any defects introduced. Based on surface hydroxylation and chemisorption theory, material removal mechanism of quartz glass in the elastic mode is analyzed to obtain defect-free surface. Elastic contact condition between nanoparticle and quartz glass surface is confirmed from the Hertz contact theory model. Atoms on the quartz glass surface are removed by chemical bond generated by impact reaction in the elastic mode, so no defects are generated without mechanical process. Experiment was conducted on a numerically controlled system for nanoparticle jet polishing, and one flat quartz glass was polished in the elastic mode. Results show that scratches on the sample surface are completely removed away with no mechanical defects introduced, and microroughness(Ra) is decreased from 1.23 nm to 0.47 nm. Functional group Ce — O — Si on ceria nanoparticles after polishing was detected directly and indirectly by FTIR, XRD and XPS spectra analysis from which the chemical impact reaction is validated.

Wire electric discharge machining characteristics of titanium nickel shape memory alloy

Ti Ni shape memory alloys（SMAs） have been normally used as the competent elements in large part of the industries due to outstanding properties, such as super elasticity and shape memory effects. However, traditional machining of SMAs is quite complex due to these properties. Hence, the wire electric discharge machining（WEDM） characteristics of Ti Ni SMA was studied. The experiments were planned as per L27 orthogonal array to minimize the experiments, each experiment was performed under different conditions of pulse duration, pulse off time, servo voltage, flushing pressure and wire speed. A multi-response optimization method using Taguchi design with utility concept has been proposed for simultaneous optimization. The analysis of means（ANOM） and analysis of variance（ANOVA） on signal to noise（S/N） ratio were performed for determining the optimal parameter levels. Taguchi analysis reveals that a combination of 1 μs pulse duration, 3.8 μs pulse off time, 40 V servo voltage, 1.8×105 Pa flushing pressure and 8 m/min wire speed is beneficial for simultaneously maximizing the material removal rate（MRR） and minimizing the surface roughness. The optimization results of WEDM of Ti Ni SMA also indicate that pulse duration significantly affects the material removal rate and surface roughness. The discharged craters, micro cracks and recast layer were observed on the machined surface at large pulse duration.

Measurement Analysis in Electrochemical Discharge Machining （ECDM） Process： A Literature Review

Electrochemical discharge machining is considered to be a hybrid machining process that combines with EDM and ECM （electro chemical machining）, called ECDM. The material removal is based on two phenomena： electrochemical dissolution of the material and thermal erosion of electrical discharges that occur between the cathode ＆ anode electrodes. This process is better used for machining of non conducting materials efficiently. In this research paper shows that a brief literature review study of various measuring instruments used for analysis of various parameters of the electrochemical discharge machining process on various types of materials, tool material, input ＆ output parameters such as surface roughness, surface texture, material removal, tool wear etc..

Material Removal Rate Prediction of Electrical Discharge Machining Process Using Artificial Neural Network

This article presents an Artificial Neural Network （ANN） architecture to model the Electrical Discharge Machining （EDM） process. It is aimed to develop the ANN model using an input-output pattern of raw data collected from an experimental of EDM process, whereas several research objectives have been outlined such as experimenting machining material for selected gap current, identifying machining parameters for ANN variables and selecting appropriate size of data selection. The experimental data （input variables） of copper-electrode and steel-workpiece is based on a selected gap current where pulse on time, pulse off time and sparking frequency have been chosen at optimum value of Material Removal Rate （MRR）. In this paper, the result has significantly demonstrated that the ANN model is capable of predicting the MRR with low percentage prediction error when compared with the experimental result.

Study of biological safety of scaffold material with heterologous deproteinized bone

To evaluate the biological safety of manufactured heterologous deproteinized bone and to provide an experimental basis for clinical applications. Methods ： Deproteinized bone （ 10 mm） and leaching liquor were made from pig ribs with a series of physical and chemical methods, then were evaluated through acute and subacute toxicity test, hemolysis test, pyrogen test, intracutaneous test, intramuscular implantation test and cytotoxity test. Results ： No obvious toxicity, hemolysis, pyrogenic characteristics, skin irritation, inflammatory reaction after intramusclar implantation and cytotoxity were observed. Conclusions： The heterologous deproteinized bone has good biological safety and meets all the demands of scaffold material for tissue engineering.

Kinematics constrained five-axis tool path planning for high material removal rate

Traditional five-axis tool path planning methods mostly focus on differential geometric characteristics between the cutter and the workpiece surface to increase the material removal rate(i.e.,by minimizing path length,improving curvature matching,maximizing local cutting width,etc.) . However,material removal rate is not only related to geometric conditions such as the local cutting width,but also constrained by feeding speed as well as the motion capacity of the five-axis machine. This research integrates machine tool kinematics and cutter-workpiece contact kinematics to present a general kinematical model for five-axis machining process. Major steps of the proposed method include:(1) to establish the forward kinematical relationship between the motion of the machine tool axes and the cutter contact point;(2) to establish a tool path optimization model for high material removal rate based on both differential geometrical property and the contact kinematics between the cutter and workpiece;(3) to convert cutter orientation and cutting direction optimization problem into a concave quadratic planning(QP) model. Tool path will finally be generated from the underlying optimal cutting direction field. Through solving the time-optimal trajectory generation problem and machining experiment,we demonstrate the validity and effectiveness of the proposed method.

Atomistic investigation of ablation of amorphous polystyrene under femtosecond laser pulse

In the present work we elucidate the thermodynamic mechanisms of femtosecond(fs)laser ablation of amorphous polystyrene by means of molecular dynamics(MD)simulations.The effects of extrinsic parameter of laser pulse intensity and intrinsic parameter of molecular architecture on the laser ablation are further studied.Simulation results show that the laser ablation-induced polymeric material removal is achieved by evaporation from the surface and expansion within the bulk.Furthermore,inter-chain sliding and intra-chain change also play important roles in the microscopic deformation of the material.It is found that both the laser pulse intensity and the arrangement of phenyl groups have significant influence on the fs laser ablation of polystyrene.

2D/2D heterostructured photocatalyst: Rational design for energy and environmental applications

Two-dimensional/two-dimensional(2D/2D)hybrid nanomaterials have triggered extensive research in the photocatalytic field.The construction of emerging 2D/2D heterostructures can generate many intriguing advantages in exploring high-performance photocatalysts,mainly including preferable dimensionality design allowing large contact interface area,integrated merits of each 2D component and rapid charge separation by the heterojunction effect.Herein,we provide a comprehensive review of the recent progress on the fundamental aspects,general synthesis strategies(in situ growth and ex situ assembly)of 2D/2D heterostructured photocatalysts and highlight their applications in the fields of hydrogen evolution,CO2 reduction and removal of pollutants.Furthermore,the perspectives on the remaining challenges and future opportunities regarding the development of 2D/2D heterostructure photocatalysts are also presented.