弹体成形工艺数字化设计系统的开发与实践

针对弹体成形工艺的特点,引入基于知识的工程技术,通过将成形工艺知识、数据及经验集成到知识库,研究开发了弹体成形工艺数字化设计系统。简要介绍了系统的技术原理和特点,并结合某型大口径弹体成形工艺,应用了该系统进行设计,达到了提高设计效率、降低开发成本的目的。     

金属塑性成形三维有限元模拟软件3D - PFS的开发

金属塑性成形过程的三维有限元模拟仿真是否有效的关键在于快速适用的算法和有效的模拟系统.介绍了自主开发的三维刚塑性/刚粘塑性有限元模拟分析软件3D-PFs的组成及关键技术问题的处理,并给出了计算实例.结果表明:利用该系统可实现对体积和板料成形过程的模拟分析,获得成形过程中材料在模腔中的流动情况及成形规律,该系统是研究金属塑性成形的有效工具.     

金属体积成形的无网格Galerkin模拟

为避免金属体积成形有限元法模拟中网格畸变造成网格重划和模拟精度降低,采用无网格法模拟金属体积成形.利用无网格法近似位移场,建立金属体积成形的无网格法连续性控制方程,采用罚函数法施加本征边界条件和体积不变条件,基于Markov变分原理推导了金属体积成形的无网格Galerkin求解列式.用数值计算法求解该列式,实现金属体积成形的无网格模拟.数值结果表明,无网格法能有效处理金属体积成形中出现的大变形,避免了网格畸变和重划,具有较高的模拟精度.     

药筒精密成形工艺数字化设计系统

介绍了药筒工艺数字化设计系统的特点、设计流程和各功能模块的主要功能。该系统在药筒成形工艺和模具设计过程中融合了基于规则的推理与基于实例的推理,可智能完成工艺参数计算,半制品与模具参数化建模,同时为设计者提供有效的精密成形工艺设计知识和经验帮助,大幅提高了该类零件成形工艺和模具设计效率。     

有限元方法在金属塑性成形中的应用

有限元法是应用于金属塑性成形数值模拟中的一种有效的数值计算方法.详细介绍了弹塑性、刚塑性、粘塑性3种有限元法.刚塑性有限元法适用于大塑性变形,包括板带、型钢轧制和环件轧制的模拟分析等.弹塑性有限元法在金属塑性成形数值模拟中应用最广.与刚塑性方法相比,弹塑性有限元法还能有效处理卸载问题,计算残余应力和应变.而粘塑性有限元法适用于金属热变形或强化不显著的软金属变形.同时,结合国内外最新的具体实例说明了这些方法在金属塑性成形领域中的具体应用,展望了有限元方法在金属塑性成形中的发展.     

不同基板预热温度对激光金属沉积成形过程温度场的影响

为降低成形过程的热应力,抑制成形过程裂缝的产生,减小成形过程试样和基板的翘曲变形,激光金属沉积成形往往需要进行基板预热,因此研究不同基板预热温度对激光金属沉积成形过程温度场的影响具有非常重要的意义．根据有限元分析中的“单元生死”技术,利用APDL编程建立了基板预热对激光金属沉积成形过程温度场影响的三维多道多层数值模拟模型,详细分析了基板未预热和分别预热到200,300,400,500,600 ℃时对沉积成形过程温度场和温度梯度的影响．通过中国科学院沈阳自动化研究所自行研制的激光金属沉积成形系统和基板预热系统,在与模拟过程相同的参数下,利用镍基合金粉末在基板未预热和分别预热到300,400,500,560 ℃时进行了成形试验,试验结果跟数值模拟结果吻合较好．     

知识库构建工具软件的设计与实现

人工智能研究领域之一的专家系统在工程设备上的应用需求较为广泛,但满足用户需求的应用实例很少,主要原因在于知识库构建复杂且困难,其质量得不到保障。针对这个问题,研究了知识获取存在的问题,开发了以故障树为核心表达方式的知识库构建工具软件,实现了故障诊断功能。根据工程实际需要,采用J2EE技术开发了一套B/S（browser/server,浏览器/服务器）模式知识库构建工具软件,并对知识库各模块进行了需求分析设计,包括知识模型的数据结构设计和业务层逻辑方法的设计。此外,还探讨了知识模型的多样性表达,以3种命名方式来表达完整的故障树。最后,通过实例说明了该知识库构建工具软件的可行性。研究结果表明：知识获取模块采用故障树表达方式,有利于知识库质量的提高;选择网页Web形式,可以实现多用户/多工位知识编辑和输入,显著提高知识获取效率。该知识获取辅助系统具有强通用性,为领域专家和工程师构建知识库提供了有力支持。     

数值模拟锻造成形的关键技术及应用

介绍了锻造成形数值模拟中的刚(粘)塑性有限元法的基本理论,对模具型腔信息描述、网格划分、边界条件处理等数值模拟中的关键技术做了全面系统的总结,分析比较了处理上述问题的各种方法.并通过实例介绍了应用模拟中的关键技术解决实际锻造问题的情况.     

轿车后围板成形过程数值模拟及参数优化

为提高轿车后围板零件的成形质量和设计效率,采用单向拉伸试验,测定了板料的力学性能参数,并对测量参数的有效性进行了验证;基于测量的参数,对该零件的冲压成形过程进行了数值模拟,改进了拉延筋的受力并优化了工艺和模具参数;对零件成形之后的回弹进行了研究,并对回弹变形进行了补偿.研究结果表明:采用测定的参数能有效地提高数值模拟的精度;优化拉延筋的受力及成形参数,可以提高成形件的质量;利用补偿法可以有效的补偿零件的回弹变形;经验知识与数值模拟相结合的优化方法是提高产品质量及工艺设计效率的有效途径.     

基于知识工程复杂产品开发过程的模型研究

 为了提高复杂产品开发的效率,驾驭复杂产品开发过程各个环节相互关联的复杂性,提出一种基于知识工程的复杂产品开发过程新模型.该模型把知识工程理论融入复杂产品开发全生命周期过程中,通过知识推理技术从数据库和知识库中获取相应开发阶段的知识和数据来驱动和指导整个复杂产品开发过程,以更好地重用设计知识.研究了该模型的关键技术,包括复杂产品开发知识处理技术和基于知识的CAD/CAM/CAE/CAPP集成技术,提出了两种知识处理方法,即基于规则-对象-框架的知识处理方法和基于规则-实例的知识处理方法,并研究了相应的推理算法;以知识库、数据库、规则库和实例库为基础,通过PDM,STEP中型文件、规则、实例和知识等,实现CAD/CAM/CAE/CAPP集成.最后,通过数据库技术、编程语言VC# . NET和CATIA软件实现了隧道掘进机（TBM）主机的快速设计系统,有效地减少了隧道掘进机主机开发的复杂性和缩短开发周期,以TBM主机为应用实例进一步介绍该模型的合理性和有效性.     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...