冰箱内胆真空成型凹模设计制造

塑料板材在凹模上借助柱塞进行真空成型,从而获得所需制品。对几何尺寸和形状要求不甚严格的冰箱内胆不失为较好的成型方法,与凸模成型相比有成本低、表面质量好的优势,广泛应用在家电行业。现对冰箱内胆真空成型凹模设计制造过程进行研究。     

建筑文化保存又一成功案例——杭州胡雪岩宅邸修复竣工

杭州修复了胡雪岩宅邸这一有名的历史建筑,为历史文化名城增添了精彩的内容,也为可持续发展做出了贡献。胡雪岩宅邸是江南晚清豪宅的代表作,建筑创作上颇有特点,此次对其进行科学复原整修“模型保护”,实是具有科学价值、历史价值、艺术价值的佳举。     

Intelligent desktop NC machine tool with compliant motion capability

In this paper, a new desktop NC machine tool with compliance control capability is presented for finishing metallic molds with small curved surface. The NC machine tool consists of three single-axis robots. Tools attached to the tip of the z-axis are ball-end abrasive tools. The control system of the NC machine tool is composed of a force feedback loop, position feedback loop and position feed-forward loop. The force feedback loop controls the polishing force consisting of tool contact force and kinetic friction force. The position feedback loop controls the position in pick feed direction. Further, the position feed-forward loop leads the tool tip along cutter location data. In order to first confirm the application limit of a conventional industrial robot to a finishing task, we evaluate the backlash that causes the position inaccuracy at the tip of an abrasive tool, through a simple position/force measurement. Through a similar measurement and a surface following control experiment along a lens mold, the basic position/force controllability with high resolutions is demonstrated. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

城市绿地系统规划塑造城市特色

从城市特色及其构成要素的把握与辨识出发,分析了城市特色危机的原因、城市绿地系统规划缺乏特色的内在因素和城市绿地系统规划塑造城市特色的意义。阐述了绿地系统规划塑造城市特色的实践策略:即梳理城市自然脉络、挖掘地域性自然地理特色,构建以城市绿地系统为先导的城市空间结构,强化城市生态绿地空间格局、塑造结构特色,实现在自然环境中寻找特色;保护并营造城市整体文化风貌,通过绿地系统保育城市文化,实现在人文环境中塑造特色;通过城市绿地系统详细规划与园林设计层次特色的构建,实现在人工环境中发展特色。     

注塑模具的绿色制造方法研究

在对绿色制造概念介绍的基础上 ,结合注塑模具自身的特点 ,具体阐述了基于绿色制造的注塑模具设计与制造的原则与方法。指出模具设计的标准化、面向可回收和拆卸的设计和模具CAD/CAPP/CAM一体化等技术是实现绿色设计的根本途径 ;先进制造技术与绿色思想的结合是绿色工艺的必然。在这种原则与方法的指导下 ,注塑模具将更易于达到高质量、短周期、低成本的目标     

Influence of B2O3 on viscosity and structure of the CaO–Al2O3-waste electrolyte (WE) based melt

The fluorides contained waste electrolyte (WE) from the electrolytic aluminum industry can be used as a substitution of fluorite (CaF₂) in the newly designed mold flux. In this study, the influence of B₂O₃ on viscosity and structure of CaO–Al₂O₃-WE based melt was investigated. Results show that the viscosity of mold flux melt decreases with both increasing temperature and B₂O₃ content. The apparent activation energy (E_a) also reduces from 78.96 ± 1.75 to 55.26 ± 2.79 kJ/mol with the addition of B₂O₃ from 0 to 7 wt%. The analyses of fourier transform infrared (FTIR) and Raman spectroscopies suggest that the lower symmetry of the original aluminate and silicate structure due to the insertion of [BO₄]-tetrahedral and [BO₃]-triangular, and the formation of more non-bridging oxygen (O⁻) and 2D structural units in the network with the addition of B₂O₃, deceases the viscosity and E_a of the CaO–Al₂O₃-WE Based Melt.     

Wear and friction behavior of CrTiN/TiCN and CrTiN/CrCN multilayer composite coatings

Multi-layer CrTiN/CrCN and CrTiN/TiCN coatings were deposited on 2379 and SLD steels by cathodic arc physical vapor deposition (arc-PVD) in different thicknesses. Coatings are mechanically, physically, and chemically characterized by nanoindentation, optical microscope, atomic force microscope (AFM), and scanning electron microscope/energy-dispersive X-ray (SEM/EDX) analyses. The crystal structure of the coatings was investigated by X-ray diffraction (XRD) analysis. Wear and friction characterizations were performed via reciprocating tribometer tests under 2.4 and 3.0 GPa Hertzian contact pressures at the unlubricated conditions. Results showed that CrTiN/CrCN coatings demonstrated excellent wear resistance and friction coefficient (COF) at elevated contact pressures both on 2379 and SLD steels.     

430不锈钢用连铸保护渣渣圈形成长大机理分析和控制措施

针对430不锈钢(0.03～0.04C,16～17Cr)生产过程中渣圈粗大的问题,利用电感耦合等离子体发射光谱仪、半球点熔点仪、粘度仪等设备对比分析了保护渣与渣圈的化学成分与理化性能,通过电子探针观测渣圈的微观结构,探究渣圈形成长大的机理。研究发现：除渣圈C含量0.53%和原渣C含量2.87%外渣圈成分与原渣无明显变化,但粘度与熔点均有所降低,渣圈约70%的区域由烧结相构成,其余30%为结晶相,主要由枪晶石与黄长石构成。烧结相的大量粘结是渣圈形成长大的主要原因。提高保护渣中预熔料比例至70%～80%及炭黑含量≥2%,并在生产中进一步稳定保护渣熔化过程,可有效抑制渣圈长大。     

Crystallization behavior and melt structure of typical CaO–SiO2 and CaO–Al2O3-Based mold fluxes

Crystallization behavior and melt structure of two typical mold fluxes A (CaO–SiO₂-based) and B (CaO–Al₂O₃-based) for casting high-aluminum steel were investigated using double hot thermocouple technology (DHTT), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The results suggest that the crystallization temperature of Flux B is higher, and its crystallization incubation time is shorter compared with Flux A. The precipitated phase in Flux A is CaSiO₃, whereas BaAl₂O₄ and Ca₂Al₂SiO₇ form in Flux B. The structure analyses suggest that the degree of polymerization of Flux A is larger than that of Flux B. In addition, the major structural units of Flux A are Si–O–Si, Q₀^Si, Q₁^Si, Q₂^Si and Q₃^Si, but those of Flux B are mainly aluminate (Al–O–Al, Al–O^-), aluminosilicate (Al–O–Si) and silicate units (Q₀^Si, Q₁^Si, Q₂^Si and Q₃^Si). These different melt structures are the main reasons why the precipitated phases in these two mold fluxes are different, and the crystallization ability of Flux A is weaker than Flux B.     

连铸凝固传热全过程数值模拟与控制

基于传热学、凝固理论、熔渣理论,建立了凝固传热有限差分数值模型,对连铸全过程进行热状态、凝固状态分析及工艺控制,模型考虑了钢的热物性参数随温度变化的关系.并根据连铸冶金准则和目标温度控制进行二冷优化,获得合理的温度分布和二冷水量分布,实现最佳铸坯品质,同时针对不同钢种的凝固特点,对保护渣性能进行设计.计算值同现场实测数据进行对比,有较好的一致性.最后研究了浇注温度、拉坯速度、二冷配水等工艺参数对铸坯表面温度、液芯长度和凝固坯壳厚度的影响,以及浇注工艺对连铸保护渣指标的影响.