槽轮组合驱动的取箱板机构的设计及运动分析

提出了一种新的槽轮组合驱动的取箱板机构.用解析法对其中的槽轮机构进行了计算机辅助设计.推导出了取箱板机构中执行构件的位移、速度、加速度计算公式,在Matlab/Simulink环境下对该机构的运动参数进行了计算,给出了执行构件的位移、速度和加速度线图.运动分析结果表明取箱板机构满足设计要求.     

金属成形加工机械执行机构的仿真与动力学分析

目的应用图解法对金属成形加工机械执行机构进行设计,并基于ADAMS和Pro/E软件对机构进行建模仿真及分析。方法根据测量出各铰链受力情况选取典型构件作为柔性构件,在ADAMS柔性模块中对相应刚性构件进行柔性替换,并比较冲头的位移、速度、加速度、曲柄力矩等曲线。结果当机构高速运转时,原动件速度为360(°)/s,柔性构件对冲头的位移、速度、加速度都造成了影响,其中对位移曲线影响不大,对速度、加速度曲线影响明显,对机构的稳定性造成了一定影响。结论当设计高速机构时,必须考虑构件的柔性因素对机构运动特性的影响。     

用回路法分析自动模切机双肘杆机构

为了研究模切机的双肘杆机构的运动规律,根据回路法的基本原理,提出了用回路法分析复杂连杆机构运动规律的方法,描述了回路法的基本原理与实际应用.用回路法分析模切机的双肘杆机构,避免了对机构的拆分.基于回路法建立了模切机双肘杆施压机构的运动数学方程,并绘出了双肘杆机构部分构件位移、速度、加速度的运动曲线.     

高速制袋机关键机构运动学分析

以制袋机热封及切刀传动机构为研究对象,根据运动特点建立了机构模型。通过热封构件运动过程中满足的约束方程,得到了热封构件位置、速度及加速度解析表达式,并进行了算例分析及Pro/ E 运动学仿真。在保证热封构件一定行程要求的基础上,对热封构件加速度进行了优化分析。结果表明,改变机构中构件设计参数可以降低热封构件运动加速度峰值。为机构动力学及振动分析提供理论基础。     

给袋式包装机撑袋空间组合机构的运动分析

目的为了使给袋式包装机更加精准、平稳地撑袋与落料。方法通过建立撑袋机构的数学模型,分析了撑袋机构末端执行件的运动特性,以矩阵坐标变换法推导出撑袋执行件的位移、速度、加速度计算公式,并通过Matlab编程得出了撑袋机构的运动学曲线图。结果升降速度和加速度曲线连续,旋转速度曲线连续,加速度曲线虽不连续,但最大加速度较小。结论运动分析表明,采用该双凸轮-连杆空间组合机构作为撑袋工位的执行机构,可以精准、平稳地完成撑袋所需的运动轨迹,实现撑袋机构的预期功能。     

纸杯机典型机构的运动分析及仿真

纸杯机工作过程主要由曲柄摇杆机构完成,为确保其工作可靠和运动平稳,采用理论推导和数值模拟相结合的方法,对其典型机构进行了运动分析,建立了数学模型.分析了滑块的位移、速度及加速度,计算结果与实测值相吻合,证明了数学模型的正确性.并采用运动分析软件分析了纸杯加工组合机构的运动与动态特性,绘制了速度、加速度曲线,为纸杯机设计与改进提供了重要的数据.     

滑阀机构运动分析及动平衡计算

由于解析法进行机构运动分析时,需要对位移关系式二次求导,求解过程复杂而又抽象,为此,本文着重介绍了一种新的方法避开复杂的二次求导,即根据速度多边形、加速度多边形直接列出速度、加速度的函数关系式,这种方法形象直观,简单方便,不易出错。现以滑阀泵为例,进行运动分析,然后介绍一种动平衡方法,即计算出平面运动的构件在转轴运动一周内沿转轴的平键方向、以及垂直于平键方向的两个平均惯性力,配重块产生的离心力等于这两个平均惯性力的合力时振动最小。     

基于UG的三棱锥袋式包装机成型模具运动仿真

利用先进的三维UG软件对三棱锥袋式包装机成型模具进行实体建模,虚拟装配并对该结构加以运动学分析,在此基础上运用UG的仿真模块实现包装机成型模具的运动仿真,最后将相关运动构件的位移、速度、加速度变化情况以图表的形式输出.分析结果对缩短产品的开发周期、提高设计质量有指导意义.     

恒张力送料机构力学分析和控制系统设计

为了使纸张在输运中有良好的稳定性、确保切纸的几何尺寸,应用自动控制技术和检测技术对常用切纸机构的恒张力送料机构进行了改性设计.对切纸机恒张力送料机构的力学特性作了详细分析并在此基础上给出了其驱动电路的设计原理和方法.     

单侧变截面辊弯成形系统的运动分析

对直线电机驱动的单侧变截面辊弯成形系统进行了运动分析。应用正解法分析了末端轧辊的位移、速度、加速度等受直线电机相关参数的影响,并列出了相关的运动方程。应用Matlab语言描绘出了末端轧辊的运动参数的变化曲线,通过曲线对比,分析了直线电机的各个运动参数的变化对末端轧辊速度、加速度等影响;分析并探讨了有关的结构参数的变化对末端轧辊的位移、速度、加速度的影响。     

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.     

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...     

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.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

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.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

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.……     

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.