试论车轮的逐步成形技术

简要叙述了车轮逐步热成形技术 ,着重对锻轧成形各工步的变形特征及成形力的确定进行了分析 ,并以 12 0 km/ h车速的 84 0 HDS型车轮为例进行了计算。     

Design and fabrication of a silicon-based direct methanol fuel cell with a new cathode spoke structure

In this paper, a self-breathing micro direct methanol fuel cell (μDMFC) featuring a new cathode current collector with a spoke configuration is presented to improve cell performance. Simulation results show that the new spoke structure can effectively increase the efficiency of oxygen mass transport and exhibit higher pressure than the conventional perforated structure. The water transfer to the proton exchange membrane (PEM) is promoted to reduce the PEM resistance with the increase in the membrane water content. Additionally, the effects of the spoke blades on performance were evaluated to determine the optimal cathode structure. The self-breathing μDMFCs with conventional and new cathode structures were fabricated using silicon-based micro-electromechanical system (MEMS) technologies and tested at room temperature with 1 M methanol solution. The experimental results revealed that the spoke cathode structure exhibits significantly higher performance than the conventional structure, showing a substantial 30% increase in peak power density.     

论数据仓库的数据架构设计

数据架构设计是数据仓库技术的核心工作之一,本文结合通信企业数据仓库系统的建设案例,简要论述数据架构的基本原理和主要设计特点。     

SOLIDCast在轮辐铸造工艺设计中的应用

运用SOLIDCast进行轮辐的铸造工艺设计,通过SOLIDCast对工艺的充型及凝固过程进行模拟,分析了缺陷形成的原因.对工艺进行了优化:增加冷铁、选用适当的浇注时间.用优化后的工艺投入生产,实际生产出的铸件外表光洁、加工后没有铸造缺陷,证实了优化后的工艺是合理的.     

高强钢钢圈轮辐的拉深成形数值模拟

为达到减重与降耗的目的,汽车钢圈趋向采用高强度钢。其成形性能有所不同,冲压工艺参数有待重新研究。依据对轮辐结构的特点进行分析,拟定其冲压成形工艺。在建立轮辐三维模型的基础上,以Dynaform有限元分析软件为分析平台,对其关键的冲压工序:拉深、局部成形与翻边进行了数值模拟,并对影响轮辐冲压工艺的主要参数:凹模圆角半径、压边力、摩擦系数与冲压速度进行优化。模拟结果与实测结果的对比说明了有限元数值模拟的可行性和新工艺参数的合理性。     

大型齿轮铸造轮辐裂纹分析与计算

重型机械设备经常应用大型齿轮传动。为节约制造成本 ,一般齿圈用合金钢锻造 ,轮芯用铸铁或铸钢制造 ,然后用过盈配合组装 ,如何确定此种结构齿轮轮辐的强度 ,迄今尚无规范的计算方法。结合某轧钢厂主传动系统大型齿轮轮辐裂纹分析 ,本文提出一种计算方法 ,并用 Super SAP软件进行有限元计算复核。两者的计算结果符合良好 ,并且定量地解释了轮辐裂纹产生的原因     

Spoke012超导腔低温调谐器的研制

调谐器是超导高频系统中的关键设备之一,其功能是调节超导腔的频率。在Spoke012超导高频系统中,我们研发了一个在低温环境下运行的特殊调谐器。该调谐器由操作原理不同的两个部分组成,一个是步进电机驱动的粗调谐部分,另一个是压电陶瓷驱动的细诃谐部分。这两个部分串联放置,可达到粗调约200kHz和细调约5Hz的调谐精度。本文报道该低温调谐器的基本参数、设计方案及性能测试结果。     

C-ADS注入器I快调谐控制方法研究

介绍了麦克风效应和洛伦兹力作用对C-ADS注入器I的Spoke012超导腔的影响以及腔的压电陶瓷快调谐传递函数的特性,并详细叙述了依据传递函数特性搭建频率控制基本环路及利用阻尼技术来对腔的特定频率边带进行抑制的方法。所设计的PI控制基本环路和特定频率边带抑制环路在实际运行中得到使用,前者有效抑制了低频振荡,后者抑制特定频率振荡幅度达到15 d B。     

Three-dimensional thermocapillary-buoyancy flow in a shallow molten silicon pool with Cz configuration

In order to understand the characteristics of surface patterns on silicon melt in Czochralski furnaces, we conducted a series of unsteady three-dimensional numerical simulations of thermocapillary-buoyancy flow of a shallow molten silicon pool with Czochralski configuration (depth d = 3 mm). The crucible sidewall is maintained at constant temperature. Bottom and free surfaces are adiabatic or allow heat transfer in the vertical direction. The simulation results indicate that two flow transitions occur with increasing the radial temperature difference along the free surface. At first, the steady two-dimensional flow becomes steady three-dimensional flow and then oscillatory three-dimensional flow. The critical conditions for the onset of the instability were determined. Characteristics of the steady and the oscillatory three-dimensional flows were discussed.     

Fast deposition of microcrystalline silicon films with preferred (2 2 0) crystallographic texture using the high-density microwave plasma

A novel high-density and low-temperature microwave discharge utilizing a spoke antenna has been applied for the fast deposition of microcrystalline silicon (μc-Si:H) films with preferred (2 2 0) orientation. Systematic deposition studies were performed from pure and H₂-diluted SiH₄ systems with microwave power, total pressure, H₂ dilution ratio and substrate temperature as variables, combined with plasma diagnostics using optical emission spectroscopy and Langmuir probe techniques. The effects of deposition parameters on the film crystallinity, crystal orientation and defect density are demonstrated.