机械螺纹类零件的数控机床加工技术探讨

随着科学技术不断发展的今天,数控机床成为零件生产加工过程中不容忽视的重要生产设备以及生产工艺。这种生产加工工艺不仅能够优化整个生产加工的具体工艺方式,同时还能够极大地提高整个零件的具体质量,而且还能提高整个生产效率。因此,数控机床在我国生产制造业中起到的作用越来越突出。所以本文主要对机械螺纹类零件的数控机床加工工艺进行了分析研究,从而探讨我国机械螺纹类零件的数控机床加工过程中所涉及到的各种加工技术。     

碳化硅反射镜轻量化结构优化设计

本文根据某型号碳化硅主反射镜的设计要求,对比了扇形、三角形、六边形轻量化孔对镜体静态、动态性能的影响,选择了综合性能较好的三角形轻量化结构方案,利用有限元方法进行参数建模,将对镜体力学性能和质量影响较大的镜体厚度、面板厚度、筋厚度等结构参数作为设计变量,运用零阶优化方法对镜体结构进行优化设计,得到了轻量化程度高、镜面变形误差完全满足设计要求的碳化硅反射镜体。     

轻质碳化硅平面反射镜超光滑表面加工

介绍了对角线为110mm六边形反应烧结轻质碳化硅平面反射镜超光滑光学加工工艺流程。详细阐述了各个工序所使用的磨具、磨料和抛光机床工艺参数,对实际加工的轻质碳化硅平面反射镜超光滑表面进行检测,检测结果为:面形精度均方根值(RMS)为0.011λ(PV值为0.071,λ=632.8nm),表面粗糙度RMS达0.75nm。     

轻质长条形反射镜结构优化设计

为解决空间反射镜镜体质量和面形精度在轻量化设计过程中会引起相互冲突的问题,针对某型离轴三反光学系统的长条形主反射镜进行了结构优化设计研究,提出了一种基于SiC材料的中心支撑的轻量化结构,同时引入了多目标集成优化方法,以镜体质量(Mass)和面形(RMS)同时作为优化目标,得到一个反射镜最佳结构模型,其质量为2.32 kg,轻量化率达到了73.8%;然后,对反射镜支撑结构进行了结构设计和说明,并对该组件进行了仿真分析,在X、Y、Z三轴方向1 g重力工况下的RMS值分别达到2.5 nm、2.2 nm、7.3 nm,4 ℃均匀温升载荷工况下的RMS值为3.2 nm,远小于设计要求的RMS≤λ/50(λ=632.8 nm),满足设计要求。     

汽车轻量化技术的研究现状综述

近年来汽车行业的科技水平发展程度逐渐提高,汽车行业进入高速发展阶段,然而随之而来的环境和能源问题也日趋加重。轻量化技术变成了各个汽车企业提升市场竞争力的关键,作者根据近些年来汽车轻量化技术现状进行综述,主要介绍了包括轻量化材料(高强度钢、镁合金、铝合金、钛合金、塑料及复合材料)、现阶段应用于汽车制造的先进加工工艺(激光焊接技术、液压成形技术)以及发展逐步成熟、显著提高轻量化成果的结构优化(尺寸优化、形状优化、形貌优化、拓扑优化、多目标多学科优化)的使用现状以及对其发展趋势的探讨。     

音圈电机驱动的快速控制反射镜高带宽控制

分析一种音圈电机驱动的快速控制反射镜(FSM)的机械结构,由此建立其数学模型。依据模型,以不完全微分PID控制算法来消除结构谐振的不稳定影响,采用线性功率放大驱动方式,可使控制带宽超过其结构谐振频率,实现高带宽控制。实验表明,该方法应用于结构谐振频率分别为90Hz和20Hz的两种快速控制反射镜,系统的抑制带宽能分别达到315Hz和240Hz,而且该方法简单可行,通用性强。     

Manufacturing of lightweight aggregates with carbon fiber and mineral wastes

The use of carbon fiber wastes (FC) as a component to manufacture lightweight aggregates (LWAs) for concrete has been studied. Amounts of 0, 2.5, 5 and 10% (w/w) of powdered FC were added into a mineral matrix composed by 90% of granite-marble sludge (COR) plus 10% of sepiolite rejection (SEP). The mixtures were milled, kneaded with water, extruded, shaped into pellets, oven-dried and finally fired at 1100, 1125 and 1150 °C for 4, 8 and 16 min in a rotary kiln. The main technological properties of the sintered aggregates were measured. The addition of FC promoted bloating and the formation of an internal structure in which both pores and unburnt carbon fibers were present. Improvements in lightness and mechanical properties were also observed. This is the first time that carbon fibers have been embedded within aggregates, opening the way to the development of a new type of LWAs for concrete.     

Experimental and numerical study of composite lightweight structural insulated panel with expanded polystyrene core against windborne debris impacts

Natural disasters such as cyclone, hurricane, tornado and typhoon cause tremendous loss around the world. The windborne debris usually imposes high speed localized impact on the building envelope, which may harm people inside the building and create dominant openings. A dominant opening in the building envelope might cause internal pressure increasing and result in substantial damage to the building structures, such as roof lifting up or even collapse. To withstand the impact of such extreme event, the penetration resistant capacity of wall or roof panels to windborne debris impact should meet the requirements specified in the wind loading codes, e.g., the Australian Wind Loading Code (AS/NZS 1170.2:2011). In this study, a composite Structural Insulated Panel (SIP) with Extended Polystyrene (EPS) core sandwiched by flat metal skins that is commonly used in building industry was investigated. To study the structural response and penetration resistant capacity of the composite panel against windborne debris impacts, a series of laboratory tests were carried out by using a pneumatic cannon testing system. The effects of various specimen configurations, impact locations and debris impact velocities on their performance were investigated. The failure modes under various projectile impact scenarios were observed and compared by using two high-speed cameras. The dynamic responses were examined quantitatively in terms of the opening size, residual velocity of projectile, deformation and strain time histories on the back skin measured in the tests. The penetration resistance capacity of the panels subjected to windborne debris impact were examined and analyzed. In addition, numerical models were developed in LS-DYNA to simulate the response and damage of the composite SIP under windborne debris impact. Laboratory tested panels were first modeled. The test data was used to calibrate the accuracy of the numerical model. The validated numerical model was then used to conduct more numerical simulations to obtain more results such as energy absorption, impact force and vulnerability curve of the SIP against windborne debris impact.     

140单元MEMS变形镜研制及测试分析

为了满足自适应光学技术更广泛的应用需求,针对传统变形镜体积大、成本高的问题,本文研制了基于微机电系统技术的MEMS变形镜并进行了实验测试。本文研制的变形镜共有140个六边形平行板电容静电驱动器,驱动器为12×12正方形排列,间距400 μm。采用表面MEMS工艺加工了变形镜样品,并利用陶瓷PGA管壳和石英玻璃盖板对样品进行了封装,同时还研制了与之配套的小型化多通道高压驱动电源。测试结果表明,该变形镜表面PV值411 nm,RMS值78 nm,在600 nm到900 nm波段的反射率接近80%,行程1.8 μm,交连值约15%,工作带宽13 kHz,阶跃响应时间23 μs,具有体积小、成本低、响应快等优势。除了进行了单元性能的测试之外,还开环控制变形镜进行了Zernike像差的拟合测试,验证了变形镜的校正能力。结果表明,该变形镜能初步满足自适应光学系统的应用需求。

     

非贯通球形空腔型轻质仿生结构的设计及其力学性能

为设计并开发轻量型仿生复合材料,分析了东方龙虱鞘翅断面的微观结构,发现龙虱鞘翅的内部空腔结构为非贯通球形空腔。受龙虱鞘翅独特结构的启发设计了一种轻质仿生结构,球形空腔以正六边形的形式分布于该结构内部。为考察该仿生结构的力学特性,引入了两种常见的中空结构,并借助有限元分析软件ANSYS分别对该仿生结构和其他两种常见的中空结构的压缩、拉伸及弯曲性能进行了有限元分析和对比研究。结果表明:该仿生结构较其他两种常见的中空结构具有更强的抗压能力、抗拉能力及更高的屈服强度,力学性能优异。该仿生结构在材料结构方面为研制新型仿生复合材料提供了仿生学参考。     

温度、炭纤维和硅土粉对轻量混凝土力学性能的影响

研究了温度、炭纤维和硅士粉含量对轻量混凝土力学性能的影响.制备了含硅土粉(质量分数0%和10%)及炭纤维(质量分数0%,0.5%,1%,和2%)的混合物,测定了高温(400℃,600℃和800℃)暴烤后轻理混凝土的压缩强度和弯曲强度.采用三个控制因素(硅土粉含量、炭纤维含量及处理温度),应用Taguchi法确定最佳条件并减少实验次数,采用方差(Anova)法确定主要实验参数与轻量混凝土力学性能的基准.结果表明:轻量混凝土力学性能最实效的参数是加热程度,而抗拉强度与抗弯强度的最佳参数各不相同.