基于VERICUT的炮管膛线电解加工阴极建模和数控仿真研究

渐速膛线电解加工的阴极需要通过实验反复修正,试验难度大,研制周期长。根据加工对象的几何参数和弹道方程建立数学模型,在Pro/E中建立阴极工作齿、炮管毛坯的几何模型并导入VERICUT,在VERICUT中设置机床参数和数控系统,添加刀具的轨迹G代码,进行加工过程的仿真,检验设计的阴极齿形状是否合理以及确定加工过程中出现的过切或欠切情况,优化阴极。研究表明,在电解加工阴极设计中采用VERICUT是一条可行的途径。     

旋转电极电解线切割加工的电解液喷液流场研究

为解决旋转电极电解线切割加工过程中电解液喷液流场不稳定造成的问题,设计了机床整体结构和电解液喷嘴结构.针对电解液喷嘴内套与外套不同夹角进行了电解液喷液流场仿真.结果表明,锥面角度15°左右最适合旋转电极电解切割加工.     

叶轮零件集成数控编程与数控加工过程仿真

探讨应用于叶轮类零件的集成数控编程与加工过程仿真技术,给出了其功能结构图与流程图,利用商品化软件SURFCAM和VERICUT构建了集成数控编程与加工过程仿真环境,并利用其实现了一个整体叶轮零件的数控编程与加工过程仿真,实际加工结果表明其能够有效解决叶轮类零件的复杂曲面加工问题.     

机匣外壁凸台电解加工分析

本文介绍了薄壁旋转件机匣外壁凸台采用电解加工方法相比传统机械加工方法的优势,并对机匣外壁凸台电解加工,确定了电解加工工艺的可行性且对电解加工过程中出现的电解加工技术问题进行分析研究及采取的改进措施。     

铝合金电解加工工艺特性实验研究

对铝合金电解加工工艺特性进行基础实验研究.通过分析影响电解加工平衡间隙的因素,利用正交试验对加工电压、电解液温度及工件进给速度对平衡间隙的影响进行了研究.实验表明:加工电压与工件进给速度的影响较大.并同时利用实验对电解加工中的重要参数平衡状态下的实际体积电化当量ηω进行了计算.     

宏程序在数控铣床加工中的应用

应用用户宏程序及仿真加工技术,设计了一个能够实现矩形外形(矩形、圆角形和键槽形)和矩形型腔(圆角形、键槽形和空白槽形)的粗加工,精加工,粗、精连续加工程序。建立了对应的参数变量,并在数控仿真软件里模拟加工轨迹后再在机床上进行了实际加工进行验证。     

面向精密加工的仿真技术研究及应用

详细阐述了计算机仿真技术在精密加工领域中应用的两个方面——加工过程动态仿真和加工过程物理特性仿真;建立了微细电火花加工仿真系统,实现微细电火花放电通道仿真,建立并分析了电火花加工的热学模型,分析了表面粗糙度与工艺参数的关系。系统在实际中得到验证,加工出微三维结构。通过电火花仿真系统,说明计算机仿真技术在精密加工研究方面的可行性和优越性。     

快速原型分层方案的优化及仿真研究

以表壳型芯的快速原型加工过程的仿真为例,在实际加工过程前,进行原型件CAD三维模型仿真,并对仿真结果进行综合的分析评价,进行分层方案的优化,实现了提高加工效率的目的。     

基于多功能加工平台的微细电解加工

电解加工在加工过程中因难以控制加工形状而很少应用在微细加工领域,为了对微细电解加工可行性进行探索,设计了多功能微细加工平台,利用多功能微细加工平台可为微细电解加工在线制作电极,采用低加工电压、低浓度的钝化电解液、高频窄脉冲电源和高速旋转的微细电极,进行了微细电解加工实验,取得了很好的工艺效果,加工间隙是影响加工精度的关键因素,设计了一个加工间隙控制伺服系统,以保证微小的加工间隙,在厚为100μm的不锈钢薄片上用微细电解打孔加工出直径为65μm的微小孔,利用微细电解加工时电极无损耗,提出采用简单圆柱微细电极进行微细电解铣削,加工出较高精度的微结构,取得了较好的工艺效果,从而验证了该微细电解加工装置的微细加工能力和方法的可行性。     

基于标准阴极特性的面齿轮阴极设计方法

目的 解决电解加工过程中,简单曲面阴极设计方法不能保证面齿轮加工精度的问题。方法 利用标准阴极进行正交试验,得出钢制面齿轮的最优电解工艺参数。利用该工艺参数对阴极重新设计,加工试件,根据试件的测量结果对原始阴极进行修形,得出最终阴极形状。结果 通过对正交试验数据进行处理,得出钢制面齿轮的最优电解工艺参数为K=20, U=10 V, v=0.6 mm/min;根据试件的误差测量结果,推导出最优修形数为0.4602。结论 此阴极设计方法所设计的阴极能保证面齿轮的加工精度,而且能够加工出IT7级精度制件,同时为复杂型面的高精度电解加工方案提供了一种可行的阴极设计方法。     

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.     

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.……     

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 ...     

Effect of Oxide Assisted Metal Nanoparticles on Microstructure and Morphology of Gallium oxide Nanowires

Several researches have been reported about the characteristic of β-Ga2O3 nanowires which was synthesized on nickel oxide particle. But indeed, recent researches about synthesis of β-Ga2O3 nanowires on oxide-assisted transition metal are limited to nickel or cobalt oxide catalyst. In this work, Gallium oxide (β-Ga2O3 ) nanowires were synthesized by a simple thermal evaporation method from gallium powder in the range of 700 - 1000℃ using the iron, nickel, copper, cobalt and zinc oxide as a catalyst, respectively. The β-Ga2O3 nanowires with single crystalline without defects were successfully synthesized at the reaction temperature of 850, 900 and 950℃ in all the catalysts. But optimum experimental condition in synthesis of nanowires varied with the kind of catalyst. As increasing synthesis temperature,the morphology of gallium oxide nanowires changed from nanowires to nanorods, and its diameter increased. From these results, we could be proposed that the growth mechanism of β-Ga2O3 nanowires was changed with synthesis temperature of nanowires. Microstructure and morphology of Synthesized nanowire was characterized by HR-TEM, FE-SEM, EDX and XRD.     

The Influence of Nitrogen and Boron Implant into Silicon Substrate on the Phase and Internal Stress of c-BN Films

Cubic boron nitride(c-BN) film was deposited on a Si (100) substrate by the RF-magnetron sputtering.The mainly problems for fabrication of c-BN films are the low purity and high intrinsic compressive stress. In order to solve the two problems, the c-BN film with the buffer interlayer was deposited on the substrate which had been implanted with nitrogen and/or boron ions. The results show: the implantation of nitrogen ions can obviously increase c-BN content and reduce the internal stress slightly; while the implantation of boron shows no obvious improvement to the content of c-BN, which can reduce the internal stress in the film obviously. In addition, it is suggested that the implantation of nitrogen and boron shows the best result, which not only can increase the content of c-BN, but also reduce the internal stress in the c-BN film obviously.