基键链方法在模具项目管理中的应用

分析了模具开发项目管理的特点,将关键链方法引入模具项目进度管理,通过实际案例应用,探讨了关键链识别、缓冲大小计算和监控等问题,并与传统关键路径法进行了对比。     

基于EVM的模具制造项目管理方法研究

针对模具是多项目并行生产且制造过程中存在大量突发事件,导致项目进度和成本与计划产生较大偏差的问题,将EVM方法引入模具制造项目管理中,描述了模具制造项目特点及在进度和成本管理方面存在的问题,回顾了EVM方法的有关原理并建立其在模具制造项目进度和成本分析预测中的应用模型,以算例来说明EVM方法在模具企业中的应用。结果表明:基于EVM的方法能够准确分析和预测模具制造项目工期和成本。     

嵌入随机概率模型的模具项目模板及其应用

针对模具生产中存在的不确定性因素,在考虑企业关键资源有限性的前提下,采用嵌入随机概率模型的模具项目模板,实现多项目调度,能够为企业制定较为准确且符合实际生产情况的项目计划。     

基于多资源约束的项目调度的模型及其算法

项目的实施过程中,经常会遇到不同项目之间对公共资源的共享与冲突,因此在资源受到限制的情况下如何调度各项目来满足项目资源需求并缩短各项目工期是非常重要的.本文在对该问题进行分析的基础上,建立了多资源约束的项目调度数学模型,并采用混合遗传算法对该问题进行求解.结合了启发式优先规则的遗传算法在保证项目任务紧前关系与资源约束的条件下,能够合理优化多项目的资源分配,从而有效地缩短项目总工期.最后,通过一个案例对模型和算法的有效性进行了验证.     

外协加工下模具项目调度方法研究

阐述了模具企业在外协加工下模具项目的调度方法。在传统生产调度方法上建立了以总成本期望值最小为优化目标的调度优化模型,设计该模型的遗传算法并进行了寻优求解,通过计算实例验证了算法的可行性和有效性,表明将外协资源考虑到生产调度中可有效减少项目群总拖期量及总成本。根据算法设计开发了一套模具项目计划制定系统,为企业实际项目制定提供决策支持。     

轮胎模具项目加工成本监控方法研究

模具返修成本的不确定性导致模具加工成本难以准确估算,在资源有限情况下对模具项目的返修环节进行研究,建立了模具项目的Markov链演化模型;基于模具项目实际情况,提出了适用于企业生产的返修成本计算方法并开发一款用于监控轮胎模具项目成本的系统,结合实例验证了该模型的有效性和实用性。     

模具项目4Ps开发体系的研究与应用

针对模具企业交货期和品质管理方面的发展瓶颈,建立了模具项目4Ps开发与管理体系,研究和总结在体系各个阶段为实现模具项目目标的手段和方法、闸门评审的重要意义,分析和归纳4Ps体系的支撑条件,阐述了6 Sigma等现代品质管理工具在模具开发中的重要作用。该体系在多家模具企业得到了实践,能有效克服模具开发过程中遇到的问题。     

模具项目随机预测系统的监视模型建立的探讨

为合理分配模具企业多项目资源,建立一个随机预测数学模型,根据状态转移矩阵的组合来预测项目最后完工可能的状态和情况.由于模具项目各个工作节点是否按照项目计划时间正常完工是相互关联的,因此,从项目的开始到结束,项目关键路径上各个相关工作节点的所有可能完工状态概率样本空间,是一个状态轨迹组合演化的轨迹空间,在有限时间内计算一定数量的工作节点不可行.通过建立一个状态转移轨迹空间约束的启发式算法实现轨迹约束.仿真结果表明:拥有一个合理的模具企业生产反馈系统,是该预测系统成功应用的关键.     

技术冲突解决原理及其在冷压模具结构创新设计上的应用

介绍了TRIZ理论中技术冲突的定义、物质-场分析方法、技术冲突解决原理等基本概念，根据该原理对某型钢丝绳铝套冷压机冷压模具结构进行概念创新改良设计。根据厂家要求，运用39个通用工程参数确定原模具设计中存在的主要技术冲突，结合40条发明原理求解模具技术冲突矩阵得到可以解决该技术冲突的一般发明原理解，并将这些一般解转化为模具结构设计的特定解，实现了对模具结构设计的创新改良，大幅度提高了该模具的使用寿命。     

基于并行工程和Multi-Agent技术的模具生产计划制定

为解决串行方式下模具生产的许多不足,提出基于并行工程和Multi-Agent技术的模具生产计划制定方法,实现了生产进度计划的动态性制定,给出Multi—Agent技术冲突的消解方法。该方法显著提高了模具设计制造效率。通过算例及结果分析,表明该方法是合理而可行的。     

连铸结晶器表面电镀技术的应用进展

对结晶器进行表面处理可以大大提高其使用寿命，电镀技术是结晶器表面处理领域的主要表面技术。分析了连铸结晶器表面电镀技术的应用发展空间，分别从面向产品性能、面向生产、面向用户的角度阐述了结晶器表面电镀技术的应用现状及发展方向。认为未来的连铸结晶器表面处理领域，电镀技术将同其他表面技术共同并存、优势互补，电镀技术仍将具有很好的开发应用前景。     

基于熵权与TOPSIS融合法的绿色刀具制造方案评估模型研究

基于绿色制造理念的刀具方案评估是推动机械加工行业实现绿色制造的重要措施。针对现有面向绿色制造的刀具方案评价研究中评价指标权重确定方面存在的不足,提出了一种新的熵权法和TOPSIS法相结合的绿色制造刀具方案评估方法。首先建立了多层次的绿色制造刀具方案评估指标体系,在此基础上,将熵权法与TOPSIS法相结合建立了基于熵权TOPSIS法的绿色制造刀具方案评估模型。最后通过方案评估实例验证了所建立的绿色制造刀具方案评估模型是合理有效的。     

机械加工工艺中设备的计算机辅助选择

提出了工艺编制中设备选择的新概念。在具体生产时根据实际生产状况选择最适当的设备，改变传统的根据加工零件特性、在工艺设计时进行固定选择的方法，很好地解决柔性生产中设备冲突和设备负荷平衡等问题。     

多Agent型CAPP系统的冲突消解

冲突是多Agent系统中存在的一种必然和本质的问题,也是多Agent系统研究的核心问题之一,基于多Agent理论的CAPP系统是CAPP技术研究的一种新趋势。本文从多个角度上研究了在多Agent型CAPP系统中冲突的类型;总结了当今在多Agent系统领域中冲突消解的策略;提出了一种冲突消解的系统模型。     

高速列车底架焊接变形的超声波法应力分析

基于单轴应力下声弹性理论,针对现有临界折射纵波应力测量方法测试区域大的缺点,提出声程差方法,克服了应力分辨率和应力场分辨率的矛盾,在当前探头制造以及超声传播时间测量精度水平下,提高了应力场空间分辨率,能够更好地获得非均匀应力场的应力梯度;使用该方法对某型高速列车底架焊接变形进行了生产现场的应力测量;对比底架上变形合格与不合格部位的应力分布,并根据应力状况计算了变形超量,指出了导致变形的原因,为后期调修提供了可靠的依据.结果表明,该方法适用于生产现场的应力评估,对焊接结构质量监控有着重要意义.     

Strain-induced martensitic transformation near twin boundaries in a biomedical Co–Cr–Mo alloy with negative stacking fault energy

Biomedical Co–Cr–Mo (CCM) alloys have been commonly used for artificial hip and knee joint prostheses, but a need to improve their biomedical inertness and wear resistance has become widely recognized. The mechanical behavior of CCM alloys is dominated by strain-induced martensitic transformation (SIMT), which causes crack initiation during plastic deformation but dramatically enhances the wear resistance in practical use. To develop more reliable CCM alloys it is essential to clarify the factors affecting the occurrence of SIMT. In the present study we have focused on the effect of annealing twin boundaries (ATBs) on SIMT behavior. We have analyzed in detail the substructures near a parallel pair of ATBs after deformation under a stress preferential for slip parallel to the ATBs. Preferential formation of ε-hexagonal close-packed (HCP) phase at ATBs in metastable γ-face-centered cubic (FCC) phase was found by both scanning electron microscopy with electron backscattered diffraction (EBSD) analysis and transmission electron microscopy (TEM). High resolution TEM images indicated that thickening of the ε-HCP phase does not proceed regularly on every second atomic plane, which would form perfect ε-phase HCP structure, but irregularly leaving a high density of stacking faults. Furthermore, the thickness of the ε-HCP phase was found to be different at ATBs on the two sides of the twin. The difference was attributed to the internal stress due to strain incompatibility at the ATBs on the basis of residual stress analysis by the EBSD–Wilkinson method and phase-field simulation of solute segregation at ATBs.     

Metallographic problems of the production of parts from continuously cast high-speed steels

It has been assumed until recently that high-speed steels cannot be produced by the method of continuous casting. Numerous attempts to use this highly efficient technology for manufacturing such steels have failed because of breakage of the cast preforms. A solution was sought in improving the design of the continuous-casting machines (CCM), increasing the level of their automation, and using rational compositions of slag-forming mixtures (SFM). The idea was that a high-speed steel can be cast only in vertical CCM. The present work concerns regimes of secondary cooling under which the structures formed in high-speed steels provide a ductility sufficient for bending the continuously cast preform without failure. Steel R6M5 cast continuously in such a machine can easily be machined into hot-rolled preforms for sheets, wire, silver-steel rods, and other final products without a forging stage. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 9, pp. 6–13, September, 1998.     

Study on the designing rules and processability of porous structure based on selective laser melting (SLM)

Porous structures are widely used in medical implant, aerospace and other light-weight manufacturing fields. The research on processability and fabricating process are of great importance to laser addictive manufacturing of porous structure, therefore formulating several rules for SLM fabrication of porous structure is necessary. This article had studied the designing rules and the key points to fabricate the porous structure precisely based on selective laser melting (SLM). In order to obtain the fabricating effect of the pre-designed porous structure, besides optimizing fabricating process, there are still a few problems to be solved gradually, including the critical inclined angle, the fabricating resolution, powder adhesion, designing unit cell and porous structure that fit for SLM process. Through the experiments of fabricating overhanging structures with different inclined angles, the critical inclined angle for designing the porous structure was got. Through designing the thin walls and cylinders with different geometrical dimensions, the SLM fabricating resolution is obtained. Then, based on the critical inclined angle and the geometrical resolution, the octahedral unit cell structure and corresponding design rules that fitted for SLM process were proposed. At last, the experiment of fabricating porous structure was conducted and the pore's sizes were also measured. The results proved that the porous structure can be well fabricated by SLM. This study provides theoretical basis for designing and manufacturing of controllable porous structure based on SLM technique.     

Interfacial reactions between molten Al and a Co–Cr–Mo alloy with and without oxidation treatment

The effect of the formation of an oxide layer on the interfacial reactions between a Co–Cr–Mo alloy (CCM alloy) and molten Al is investigated. In the absence of an oxide layer, the CCM alloy reacted rapidly and an interfacial two-layer structure formed between the CCM alloy and molten Al. Upon oxidation, a uniform (Cr,M)₂O₃ (M: doped elements) oxide layer formed on the CCM alloy surface, which effectively inhibited the reaction between the CCM alloy matrix and molten Al for more than 2 h.     

注射模协同设计系统中的冲突消解策略

目前，注射产品开发趋于多元化，许多产品的设计来源于既有的实物，并通过基于RE／CAD／CAE集成的协同，实现快速制造。在注射模协同设计过程中，由于各协同小组对设计的考虑角度、评价标准和领域知识不尽相同，从而会导致设计冲突。冲突在设计过程具有特有的正、负面影响，因此冲突消解在协同设计系统中占有重要的地位，故提出了注射模协同设计系统结构中的冲突产生、约束求解和冲突消解策略。