Reasonable Process Parameters Research Articles

Diameter prediction of removal particles in Al2O3 ceramic laser cutting based on vapor-to-melt ratio

In order to predict the particle size of molten removal in laser cutting Al2O3 ceramic plate, an atomization model based on vapor-to-melt ratio is developed to reveal the relationship between material remove forms and results during the process of vaporization-melt. Model correction of vapor-to-melt ratio with different parameters is obtained by laser cutting of 96.4% Al2O3 ceramic plate to get the slit width. The experimental verification is carried out on a JK701H Nd:YAG pulse laser cutting system by simulating under the regression correction of melt flow diameter. Micro-observation on the molten particles with different plate thickness (1.5mm, 2.0mm, 3.0mm varied with increasing of vapor-to-melt ratio) and the calculations show that the particle diameter decreases rapidly (70μm, 60μm, 35 μm) with vapor-to-melt ratio after increasing to an extreme value (80∼85μm). It is proved that there is an antagonistic relationship between kinetic and thermodynamic effect in the impact of vapor-to-melt ratio (with critical value of 0.1) on the morphology of cutting removal. The results show good agreement between atomization model and experiments with average error below 8%. The analysis verifies this model is feasible and it makes contribution to determine the reasonable processing parameters (such as the control of vapor-to-melt ratio) in laser precision cutting.

Abrasive wear of a single CBN grain in ultrasonic-assisted high-speed grinding

Research into the single grain cutting mechanism is important for understanding complex grinding mechanisms. Based on the characteristics of ultrasonic vibration, the motion equation of the grain is established, and the generated trajectory is theoretically analyzed. By adopting the method of combining high-speed grinding technology with ultrasonic vibration, abrasive wear forms of single cubic boron nitride (CBN) grains under common and ultrasonic conditions are studied. Further studies are conducted on the influence of the grain itself and the main grinding parameters on abrasive wear. Research shows that the main forms of abrasive wear during ultrasonic-assisted grinding are shearing wear and removing wear. However, common grinding leads to micro-crushing wear and a small amount of abrasion wear; the different forms of wear correspond to different grinding force signals. The greater the initial grain protrusion height, the greater is the abrasion of the protrusion; for the same grain protrusion height, the abrasive wear due to ultrasonic-assisted grinding is larger than that due to common grinding. As the grinding depth increases, the abrasive wear of both processing modes increases; however, in the case of ultrasonic machining, the abrasive wear increases slowly and is larger than that under common grinding. This study provides a certain decision basis for real-time monitoring of the ultrasonic-assisted high-speed grinding process. Additionally, it provides guidance and reference for the manufacture and selection of the grinding wheel and for the selection of reasonable processing parameters.

Tilting separation analysis of bottom-up mask projection stereolithography based on cohesive zone model

Compared with top-down stereolithography, bottom-up mask projection stereolithography can reduce the start filling volume of vat and is able to build components with high-viscosity materials. For general photosensitive materials, a separation process is required to detach the cured layer from the resin vat surface in order to accomplish the fabrication of current layer. The separation process can be achieved without damaging the part by utilizing appropriate platform motions including pulling-up, tilting and shearing, and covering inert film on the vat surface. The tilting separation is used in both industrial and academic area. However, there is a limited corresponding study compared with pulling-up separation. The mechanism of tilting separation and its effects on separation force and fabrication process are not clear. In this paper, an analytical model based on cohesive zone model was formed and a specialized experimental system was built. Experimental studies on the tilting effects on cohesive stiffness and fracture energy were conducted by collecting and analyzing separation force data. The results showed that changing exposure area function or the part fabrication orientation changed the cohesive stiffness, and increasing tilting separation velocity caused different increase in fracture energy when using different inert films. The results of this investigation can be used to choose the reasonable platform motion and process parameters by considering the part geometry and the characteristics of both inert film and materials.

Process parameter determination of the axial-pushed incremental rolling process of spline shaft

The process parameters of the axial-pushed incremental rolling process are studied in this paper to solve the problems in present production process of spline shaft. Firstly, the principle of the axial-pushed incremental rolling process is introduced. Based on the material of 42CrMo, the simplified finite element models of the process are established up. Then, the effects of process parameters and the material flow behavior during the process are investigated by finite element analysis (FEA). After that, the reasonable process parameters during the novel process (die angle 9°, feed speed 0.5 mm s−1, and speed of rolling die 25 r min−1) are determined to meet a good balance between the forming force, product precision, and processing efficiency. To verify the determined parameters, validation tests with the blank material 42CrMo were carried out on an axial-pushed incremental rolling equipment. The experimental results (tooth shape and forming force) show a good agreement with FEA results. Through the dimension measurement, the addendum and root circle diameters of formed spline shafts are 51.61, 51.72, and 51.66 mm and 48.66, 48.78, and 48.69 mm, respectively. The formed spline shafts with the determined process parameters reach to the requirement of direct use (required addendum circle diameter 51.56~51.75 mm, required root circle diameter 48.5~48.7 mm). Finally, the feasibility of the determined process parameters with other materials (no. 20 and no. 45 steel) is investigated. The dimensions of the formed spline shafts just slightly deviate from the theoretical value. This problem is solved by adjusting the feed speed and the speed of rolling die. Therefore, the determined process parameters of the axial-pushed incremental rolling process are usable for the production of spline shaft.

Theoretical analysis and experimental investigations on the symmetrical three-roller setting round process

In this paper, a series of problems about the three-roller setting round process are studied. The theoretical analysis of increasing the roundness by three-roller bending is carried out, which shows that every pipe-wall segment alternately experiences multiple times of reciprocating bending, then the process mechanism of the three-roller setting round process is elaborated upon. It is proven by the mathematical induction method that the difference of the initial curvature of each pipe-wall segment can be eliminated and unified by multiple times of reciprocating bending. The experimental results show that with the increase of the upper roller reduction and the decrease of the elastic area ratio, the residual ovality of the pipe decreases gradually. When the elastic area ratio reaches about 20 %, the residual ovality can be controlled at around 0.35 %, which is far less than the requirement of American Petroleum Institute (API) standard. The quantitative relationships between the reduction and the curvature variation and the elastic area ratio are established, so the prediction of the reduction can be realized. However, in order to get the pipe of high precision, it is necessary to greatly increase the tonnage of a three-roller setting round device, which is an aspect that the setting round equipment manufacturers and pipe manufacturers need to notice. In addition, the residual ovality has nothing to do with the initial ovality and has little relation with the lower roller spacing, and it mainly depends on the elastic area ratio and the reasonable process parameters.

Numerical simulation and experimental study of slippage in gear rolling

Gear rolling has the advantage of efficient material application, contour-related fiber orientation, and can overcome forming difficulties of gear forging. In the initial stage of gear rolling, often the slipping phenomenon occurs. Slippage and the degree of slippage significantly affect the forming quality of the tooth shape. In this paper, the applied forces on a blank in the initial forming phase of the gear rolling were analyzed, and the main factors affecting slippage were determined. Then, the quantitative evaluation index of the slippage was established. The effect of initial bite depth, friction condition, and number of teeth on the gear roller on slippage was obtained using finite element analysis. The effect of different initial bite depths and number of teeth on the gear roller on the slippage was studied experimentally. Moreover, the reliability of the finite element simulation results of gear rolling was verified. The results can provide a scientific basis for establishing reasonable process parameters, control of slippage, and improving the forming quality in gear rolling.

Experimental Study on Laser Transmission Joining between PA66GF and AISI304

Joining between polyamides (PA) and metals has potential applications in the industry. Based on PA66GF and AISI304, the experimental study of laser transmission joining of the dissimilar materials is conducted in this article. Firstly, comprehensive experiments of laser transmission joining between PA66GF and AISI304 are carried out by Nd: YAG pulsed laser source according to the central composite rotatable design method (CCRD). Secondly, the effects of the process parameters like voltage, joining speed and stand-off distance on the joint quality are analyzed by response surface methodology (RSM). Finally, mathematical models between the process parameters and the lap-shear strength and the joint width are established and based on which, the optimization of the joining process is done and the optimized results are predicted. The results show that the process parameters of laser transmission joining play a significant role in determining the joint quality; the predicted data of the models are in good agreement with the experimental results and can be of great help for the optimization of the joining process. As a result, this study could provide an effective instruction about how to choose the reasonable process parameters for enhancing the joining efficiency.

Study of Milling Time and Process Control Agent on W–Mo–Cr Pre-Alloying Powders

According to the experimental researches of dynamic friction polishing (DFP) technology, high density and hardness W–Mo–Cr alloy with strong graphitization ability of diamond can achieve a high material removal rate of diamond. In the preparation process of polishing plate, mechanical alloying (MA) method is used to synthetize pre-alloying powders by means of fierce mechanical action and supersaturated solid state reaction performed by high-energy ball milling. The effect and progress of MA are directly affected by the process parameters of ball milling. This article mainly summarizes the microstructural changes of W–Mo–Cr pre-alloying powders varying with milling time and process control agent (PCA) content, and their function mechanisms and potential causes are discussed. The reasonable process parameters of ball milling are optimized by single-factor experiments. The results show that under the conditions of 300 rpm rotation speed, 60 h milling time, and 10% PCA content, the surface activities, compositional uniformity, and grain refinement level of powders are heightened. The preparation of excellent pre-alloying powders provides early technical guarantee for the study of high density tungsten-based alloy used for DFP diamond.

Research on Laser Oxidation Melting Cutting Process of Automobile Carbon Parts

This paper deals with the study of automobile parts laser cutting process and high power laser oxidation melting cutting technology. Laser oxidation melting cutting and perforation technology was studied and laser cutting process was established. Take automobile part back end plate for example, back end plate and the material is carbon steel, the CAD/CAM simulation software was used, reasonable processing parameters, cutting parameters and perforation parameters were designed. The experimental results show that laser oxidation cutting is very effective method for automobile parts of carbon steel. The laser oxidation laser cutting technical problems and carbon materials processing technology were solved and improvement measures were summarized for the high laser oxidation melting cutting.

ELECTROCHEMICAL BEHAVIOR OF Ni2+ IN SiO2-CaO-MgO-Al2O3 MOLTEN SLAG AT 1673 K

The modern iron and steel industry produces large emissions of CO2 annually. Electrolytic reduction of molten slag containing iron oxide at high temperature using an inert oxygen evolving anode is an alternative process to reduce or eliminate the formation of CO2. In order to establish reasonable process parameters of electrolytic method for steel containing Ni, it is necessary to master the electrochemical behavior of Ni + in molten slag. However, investigations on the electrochemical behavior of Ni in molten slag at higher temperatures were very limited, which can probably be attributed to the experimental difficulties associated with the operation of high-temperature electrochemical cells. An electrolytic cell with a controlled oxygen flow and Pt, O2(air)|ZrO2 used as reference electrode was constructed integrally through a one-end-closed magnesia partially stabilized ZrO2 solid electrolyte tube. Electrochemical behavior of Ni + on Ir electrode was investigated in SiO2-CaO-MgO-Al2O3 molten slag at 1673 K by means of electrochemical techniques such as cyclic voltammetry (CV), square wave voltammetry (SWV), chronopotentiometry (CP) and potentiostatic electrolysis. The results show that both diffusion in the molten slag and electromigration in the ZrO2 solid electrolyte for the O are not rate-determining steps of electrochemi*国家自然科学基金项目51174148和武汉科技大学大学生科技创新基金研究项目14ZRA004资助 收到初稿日期: 2015-01-22,收到修改稿日期: 2015-04-27 作者简介:洪川,男, 1990年生,硕士生 DOI: 10.11900/0412.1961.2015.00065 第1001-1009页 pp.1001-1009

Influence of oxygen partial pressure on laser-induced damage resistance of ZrO2 films in vacuum

The dependence of laser-induced damage resistance of ZrO2 films in vacuum on oxygen partial pressure has been studied. Results revealed that laser-induced damage resistance of ZrO2 films in vacuum had a complicated dependent relationship with the oxygen partial pressure. And higher laser-induced damage threshold under the oxygen partial pressure of 1.0 × 10−2 Pa was a result of the combination effect of many factors, such as optical characteristics, structural property and stress property. Study indicated that reasonable process parameter being capable of balancing effectively the adverse and favorable factors was very necessary for preparing optical films with high laser-induced damage threshold in vacuum.

Carbon-contained cement “raw” meal pellets’ preheating and decomposition

This study was conducted for carbon-contained cement raw meal pellets from an actual production facility, and on heat transfer, particle cracking and the reaction process of the material balls under high temperatures. Reasonable process parameters and significant conclusions were obtained. The results suggested that (1) the residence time of materials in the preheating process should be controlled within approximately 300 s; (2) the preheating exhaust gas temperature should be controlled at 600°C, which should be conducive to reducing a large number of broken pellets; (3) higher temperatures, smaller particle sizes and greater gas velocity were helpful to a higher weight-loss ratio and an overall reaction rate; (4) pulverized coal combustion took longer time than limestone decomposition above 900°C.

同步超声复合电加工振动监测与加电间隙控制

同步超声复合电加工的关键问题之一是超声幅值的在线检测与加电间隙的在线控制；选用高速激光位移传感器测量工具头端面的振动幅值，并经数据采集卡输送至计算机中，基于LabVIEW开发监测与控制程序，通过RS232C串口对激光位移传感器公差比较器值进行在线调节，进而改变加电间隙；利用所完善的超声复合电加工系统，合理选择加工参数，对硬质合金进行超声复合电加工试验，结果表明了超声及其复合电加工技术在加工硬脆性和难加工材料的技术优势。 Ultrasonic vibration amplitude on-line measurement and inter-electrode gap on-line controlling are the key issues of synchronizing ultrasonic compound electric machining. The vibration amplitude of end face of the tool head is measured by selecting high-speed laser displacement sensors, and then these data are transferred to computer by data acquisition card; based on LabVIEW development monitoring and controlling program, it can adjust tolerance comparator set point of laser displacement sensors on-line by RS232C, and then change the inter-electrode gap. Using the optimized ultrasonic compound electric machining system, selecting the reasonable processing parameters, the processing tests are conducted with cemented carbide. The results show that the ultrasound technology and compound electronic processing technology have technical advantages in machining hard and brittle difficult materials.

3D Numerical and Experimental Investigation on Semi-Solid AlSi9Mg Alloy Slurry Prepared by Electromagnetic Stirring

To prepare semi-solid AlSi9Mg alloy slurry, we simulated electromagnetic stirring (EMS) based on a coupled 3D model of electromagnetic field, temperature field, and flow field by sequentially coupling ANSOFT and FLUENT software. Results show that magnetic flux density and electromagnetic body force (EMF) decrease and exhibit non-uniform patterns as stirring frequency increases. However, magnetic flux density and EMF increase in proportion to the stirring current but become more inhomogeneous. As EMF increases, the flow velocity and the depth of vortex in the semi-solid slurry gradually increase; thus, slurry temperature decreases. The deviation in temperature is then reduced between the center and the edge. As a result, the microstructure of the slurry evolves from coarse rosette grains to fine and spheroidal ones. By comparison, turbulent flow is generated by excessive and more unevenly distributed EMF, which causes deterioration in microstructures, such as the formation of cavities in the semi-solid AlSi9Mg alloy slurry. Based on simulation and experimental results, our conclusion is that reasonable process parameters have been obtained and verified experimentally. These results also show the validity and reliability of EMS-prepared semi-solid AlSi9Mg alloy.

Effects of parameters on the performance of amorphous IGZO thin films prepared by RF magnetron sputtering

Amorphous indium-gallium-zinc oxide (IGZO) transparent conductive thin films are prepared on glass substrates by radio frequency (RF) magnetron sputtering. The effects of seven factors, which are substrate temperature, sputtering atmosphere, working pressure, sputtering power, annealing temperature, negative bias voltage and sputtering time, on Hall mobility, transmittance and surface roughness are studied through orthogonal experiments. The results show that the effects of working pressure, substrate temperature and sputtering atmosphere on performance of films are the most prominent. According to the experimental results and discussion, relatively reasonable process parameters are obtained, which are working pressure of 0.35 Pa, substrate temperature of 200 °C, sputtering atmosphere of Ar, sputtering power of 125 W, sputtering time of 30 min, negative bias voltage of 0 V and annealing temperature of 300 °C.

Modeling and Optimization of Laser Direct Joining Process Parameters of Titanium Alloy and Carbon Fiber Reinforced Nylon Based on Response Surface Methodology

A laser direct joining (LDJ) experiment of titanium alloy (Ti-6Al-4V) and carbon fiber reinforced nylon (PA66CF20) is presented here using diode laser equipment. Experimental design and experiment of LDJ are carried out according to a single process parameters range obtained from the previous experiment. Response surface methodology (RSM) in Design-Expert v7 software is adopted to establish the mathematical model between LDJ process parameters and joint quality. Then the interaction effects of joining process parameters (laser power, scan speed and stand-off distance) on joint quality are investigated using analysis-of-variance (ANOVA), and the result shows that the interaction effect of laser power and scan speed on joint quality is the greatest. Finally, the predicted values from the mathematical model established by RSM are compared with the experimental values, and the process parameters are optimized to obtain the strongest joint strength. The result suggests that the predicted values are in good agreement with the experimental ones. The purpose of predicting and optimizing joint quality based on reasonable process parameters is achieved.

Modeling and Optimization of Mask Assisted Laser Transmission Micro Joining Process

This article uses semiconductor laser for mask assisted laser transmission micro joining PET and PET with clear weld absorbents, the mask slit width is 0.3mm, using CCD to plan experimental design. The mathematical model of joining process parameters with joint strength and joint width was established using response surface methodology. Experimental verification was also done. The actual joint width was compared to mask slit width and the process parameters were optimized. The results show that the mathematical model can response the relationship between process parameters and joining quality, the mask can effectively control the joint width, reasonable process parameters can obtain high-precision, high-intensity joining quality.

A micro-ultrasonic powder moulding method to fabricate Sn–Bi alloy micro parts

The Sn–Bi eutectic alloy powder in the micro-cavity was melted by ultrasonic vibration and rapidly cooled to form micro parts; no subsequent sintering process was required. Three kinds of Sn–Bi alloy micro gears were successfully fabricated, which verified the feasibility of the micro-ultrasonic powder moulding method. The effect of ultrasonic exposure time on the microstructure and mechanical properties of the micro parts was investigated respectively by metallographic analysis, XRD and tensile testing. Reasonable process parameters for this method were determined, which were sonotrode pressure of 63.5MPa, ultrasonic output power of 2475W and ultrasonic exposure time of 1.5s.

Analysis of Axial Holding Capability about the Lengthened Shrink-Fit Holder and Cutting Tool System

Lengthened shrink-fit holder is one important part of high speeding tool system. Its gripping rigidity directly affects the quality of the processed parts and machining efficiency. Building the FEA model of axial gripping rigidity about Lengthened shrink-fit holder and Cutting tool system with UG NX to analyze the influence with different interference,speed,gripping length and thickness on axial gripping rigidity. The gripping rigidity is one important parameter of the lengthened shrink-fit holder and cutting tool system, including radial griping rigidity,torsional griping rigidity and axial gripping rigidity,the reasonable interference of shrink-fit holder is obtained by contrasting three rigidity. Research provides a certain of theoretical guidance on the design of the lengthened shrink-fit holder and cutting tool system and choosing the reasonable processing parameters.

Hybrid modelling for real-time prediction of the sulphur content during ladle furnace steel refining with embedding prior knowledge

Real-time prediction of the sulphur content of steel is of great importance for operation guidance during ladle furnace (LF) steel refining. For seeking an accurate prediction, this paper proposes to establish sulphur content prediction model in a hybrid way, where a simplified first principle model is introduced and fine tuned by data-driven modelling methods. The derived hybrid model employs optimization approach to optimize its data representation part, while prior knowledge is embedded in the form of linear constraints. An innovation of the proposed methodology is the full exploitation of prior knowledge about the process for determining reasonable process parameters. Moreover, a novel optimization approach is developed for ensuring accuracy and improving solution efficiency by the integration of genetic algorithm and successive approximation method. The proposed hybrid model possesses flexible interpretable structure and adaptive learning ability. As a result, it ensures the extrapolation property for real-time prediction and is able to provide an in-depth understanding of practical desulphurization process, making it very suitable for process monitoring and operations optimization during LF steel refining. Finally, this hybrid model is validated on recorded data from an industrial LF plant.