基于自适应遗传算法的模具制造动态调度研究

模具生产工艺复杂,生产过程动态多变,为有效求解模具制造动态调度问题,设计动态调度算法。文章首先建立简化模具企业车间作业调度问题模型,利用自适应遗传算法确定模具各工件各工序的加工方案。其次,考虑模具生产中的不确定因素,提出了局部更新和全局更新相结合的、基于滚动窗口技术的动态调度方法。最后,将算法用于求解实际模具企业车间作业调度问题,结果表明,该算法通用性强,可行性高。     

基于模具项目计划的工件热处理分批优化

针对某模具生产企业热处理车间的生产调度问题,在模具项目计划的基础上,根据热处理加工时各加工工件必须满足的各种约束条件,提出了热处理工件的分批处理规则,给出了基于降序首次适应规则的启发式算法(FFD)和主零件为中心成批策略,实验结果表明了该策略和算法的有效性,达到热处理零件批数最少的目的,从而节省生产成本。     

基于多级优先规则的模具企业动态车间作业调度算法

提出了一种基于多级优先规则的动态车间作业调度算法,在多级优先规则中,综合考虑一般优先规则的优先数、常规暂停和工件的权重,通过评价函数得出各工件的优先级进行调度。结果表明:调度结果可行,并具有较好的优化效果。对模具企业生产车间调度具有指导作用。     

柔性流水类模具零部件热处理车间多目标动态调度

考虑柔性流水类模具零部件热处理车间的任务动态到达性、多工件族不相容性及设备装载量非同等性等特点,以交货准时性、制造节能性、质量稳定性为调度目标,构建了相应的数学模型,建立了事件触发的实时调度机制,并据此提出了一类基于前摄性组批策略的启发式算法,通过嵌入多层折衷规划模型对多目标进行有效协调,最后基于MATLAB仿真试验,说明了所提方法的有效性和适应性。     

综合多路径选择与前工序作业排序的热处理多目标在线调度

以模具热处理车间及其上游多路径可选的柔性作业车间为背景,总结其为一类多路径可选的FJSP类型批调度问题。考虑热处理车间中任务到达的动态性、上游多路径的可选性,构建了反映拖期、能耗与加工质量的优化目标,建立了综合多路径选择与前工序作业排序的热处理在线调度机制。当工件在上游工序时,通过多路径选择方案的调整,可以使工件以一个更为合适的时间到达热处理车间,通过具有良好鲁棒性的嵌入直接牵引的批调度机制对当前组批进行优化,周期性的前工序作业排序方案可以对所有组批方案进行优化,算法核心根据多层折衷规划模型对多目标优化进行深度协调。仿真研究验证了该算法的有效性和环境适应性。     

考虑瓶颈工序外协的模具车间调度研究与应用

瓶颈工序是工件生产流动的窄口,直接影响产品的交货期和制造成本。模具生产为典型的多品种小批量生产方式,生产节拍难以控制,生产调度困难,瓶颈工序直接制约车间产量的提升。以最大化利润为调度目标,研究考虑瓶颈工序外协的调度算法,并在某公司模具车间进行运用,取得了较好的效益,验证了该调度算法对多目标柔性作业车间的指导意义。     

两阶段流水类型模具热处理车间的联合批调度方法

以两阶段流水类型模具热处理生产控制为背景,总结其为一类柔性Flow-shop类型批调度问题,考虑到模具热处理车间中任务到达的动态性、多工件族不相容性,构建了反映拖期和能耗的优化指标,建立了事件与周期联合调度机制,对淬火阶段生产环境的变化进行实时响应,对回火任务滚动排产,通过算法中两层折衷规划模型的嵌入,实现了对多目标的有效协调。最后通过仿真试验证明了所提方法的优越性和适应性。     

用蜂群算法实现动态作业车间调度

目前多数作业车间调度算法考虑的是静态调度,但在实际生产中车间总是处于动态变化中.文章研究利用蜂群与环境交互的模型来进行动态调度,提出了有关的算法,仿真实验结果表明这种方法适用于多批次以及各批次工件到达时间不定的情况下的作业车间调度.     

柔性制造系统工件自动搬运小车动态实时调度模型及算法

FMS的自动搬运小车实时调度问题是FMS生产调度管理中的重要问题之一。本文将FMS生产过程中工件流动的动态性和相对稳定性结合起来考虑,建立了自动搬运小车的实时调度动态数学模型。在此基础上给出小车的实时调度算法。这种算法具有调度优化程度高,计算复杂性低等优点,可以较好地解决FMS中自动搬运小车的最优实时调度问题。图2幅,表2个。     

H13钢的真空热处理

介绍了北美压铸模协会（NADCA）推荐的H13钢的真空热处理工艺，详细讨论了对热处理设备的要求，工件的装炉，热电偶的放置，奥氏体化，淬火速率与工件组织和性能的关系，回火工艺和硬度控制，模具的去应力处理，H13钢模具的热处理质量和检测，以及热处理合格证书的内容，并附有H13钢淬火组织级别图。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。