基于Zemax的新型匀光鳞甲反光杯系统设计

为进一步优化传统反光杯在匀光、防眩光等方面的问题,基于Zemax仿真软件设计出了一种匀光性能优越的鳞甲反光杯。仿真结果表明,在杯前25 m处的配光屏幕上,最大光照强度为234 lx,中心HV点的光照强度大于0.80 E_max,各指标均符合国标GB 25991—2010《汽车用LED前照灯》的要求。将鳞甲反光杯与微透镜阵列相结合,使配光屏幕上的最大光照强度减小至59.51 lx,在各项指标仍符合国家标准的情况下,该系统的光斑能量更加均匀,且中心区域的光强进一步降低,光斑边缘过渡更加柔和,防止汽车远光灯产生眩光的效果更好,可以大量应用于汽车前照远光灯。     

反光杯非圆曲线的车削加工及精度控制

反光杯零件高次及其他非圆曲线的加工及其精度控制是数控车床加工的难点问题,对于此问题,提出了一种基于加工路径细分及根据零件加工精度的要求对加工步长的长度及精度进行控制的加工方法.通过编制加工点计算程序对此方法计算数值及误差进行了理论分析,并在华中HNC-21T型数控车床上运用宏程序编程方法对实际非圆曲线反光杯零件进行了加...     

汽车座舱反光问题以及优化手段分析

基于目前常见的汽车座舱反光问题,描述反光形成的基本原理,介绍两种通用的定性、定量反光分析方法,最后针对某款多屏电子仪表板,进行了主驾屏反光分析以及优化,为该方法在整车内饰布置开发的推广使用提供了参考。     

板上芯片集成封装的发光二极管结构设计

根据板上芯片(COB)集成封装的结构特点,同时考虑反光杯结构和荧光粉涂敷方式,分析了影响COB封装的发光二极管(LED)发光性能的主要因素.针对反光杯结构的关键要素:反光杯形状、反光杯深度、反光杯角度,优化设计了LED光学结构.通过改变TracePro软件中反光杯的相关参数,模拟了不同LED的光强分布及发光效率,探讨了提高COB封装的白光LED发光效能的途径.最后,在4 mA和12 mA电流下进行了传统荧光粉涂敷方式及荧光粉远离芯片涂敷方式的对照实验.仿真及实验结果表明:采用圆锥形反光杯,反光杯深度在一定范围内略大,且反光杯角度设为30°时,LED发光性能较为优异.与传统封装方法相比,采用荧光粉远离芯片的封装方法可使发光效率提高5％左右.得到的结果对LED封装制造过程有指导意义.     

浅谈汽车多媒体显示屏的人机布置设计

主要针对汽车多媒体显示屏的人机布置设计进行研究,重点从人机视野、人机操作、反光眩目及界面设计等方面进行讲述,结合实际车型开发经验,总结多媒体显示屏在工程设计过程中的设计原则,为广大汽车设计者们提供参考。     

一种塑料包装类反光产品的视觉打光方法

食品塑料包装外膜大致分为珠光膜、亚光膜和PE膜,外包装上主要是前两种,其共同特点是在普通光源下呈现强烈的反光性,反光会产生耀眼的光斑,相机端无法获得高质量、对比度强的信息,大大阻碍视觉的识别、分选、瑕疵检测等,进而无法实现自动化的方案.阐述了一种基于球积分光源的视觉打光方案,利用球积分光源光线多方向性及漫反射特性,改变打在反光表面的光线方向和反射特性,避免同一方向直射光束的镜面反射.并用月饼识别作测试,大量实验数据证明这种方案可以有效解决塑料包装反光的问题,为实现自动化识别和分拣提供了有力保障.     

透红外冷反射镜的研制

本文介绍一种透红外冷反射镜反光杯（碗）的光学设计、光学薄膜膜系设计和镀制工艺,特别介绍镀制工艺中膜层的均匀性、冷光膜的重复性、牢固性等的影响因素和解决办法。     

覆膜角度对运动薄膜非线性振动的影响

以覆膜钢板为研究对象,主要研究运动薄膜非线性振动问题以及覆膜钢板膜层附着性能。运用ANSYS模拟不同覆膜角度对运动薄膜运动的影响以及分析各频率区间的拉、压应力变化规律,通过杯突仪检验覆膜钢板膜层的附着性能。结果表明:覆膜角度45°为运动薄膜的临界角度,其中运动薄膜在覆膜角度40°的非线性振动效果最佳;覆膜角度30°、35°运动薄膜的幅频变化规律相同,在550～1 100 Hz与1 950～2 100 Hz区间内覆膜角度30°、35°与40°运动薄膜的各轴方向应力变化相同;通过杯突实验检验覆膜角度30°、35°与40°的覆膜钢板膜层附着性能,覆膜角度40°覆膜钢板膜层性能最好。     

八招减轻电脑伤眼

遵循以下8点,可以减少电脑给眼睛带来的伤害,缓解疲劳、酸疼： 1.电脑屏幕略向下倾斜 屏幕反光会刺激眼睛,而最强的反光来自上方光线,如日光灯和阳光。把电脑屏幕向下倾斜一些,拉上窗帘,都可以减少反光。     

浮杯泵柱塞副变形的有限元分析

浮杯泵独特的结构导致其泄漏点大量增加,变形后的柱塞副密封间隙成为影响其工作性能的主要因素。在泄漏间隙理论分析的基础上利用有限元软件对三组不同柱塞腔尺寸的柱塞和浮杯在上死点和下死点两种极端位置处进行受压变形仿真,讨论变形后柱塞腔的尺寸对柱塞副间隙的影响。分析得到柱塞和浮杯变形后的变化规律,以及在密封线处浮杯的变形值约为0.8  μm和柱塞头的椭圆形变形趋势,对比得出在20 MPa的压力下直径为8 mm、深度为6 mm的柱塞腔能够使柱塞头的变形有效补偿浮杯的变形。     

Fatigue design of various type spot welded lap joints using the maximum stress

Recently, a new issue in designing spot welded structures such as automobile and train car bodies is to predict an economical fatigue design criterion. One of the most typical and traditional methods is to use a ΔP—N_f curve. However, since the fatigue data on the ΔP—N_f curve vary according to the welding conditions, materials, geometry of joint and fatigue loading conditions, it is necessary to perform the additional fatigue tests for determining a new fatigue design criterion of spot-welded lap joint having specific dimension and geometry. In this study, the stress distributions around spot welds of various spot welded lap joints such as in-plane bending type (IB type), tension shear type (TS type) and cross tension type (CT type) were numerically analyzed. Using these results, the ΔP—N_f curves previously obtained from the fatigue tests for each type were rearranged into the Δσ -N _f relations with the maximum stresses at the nugget edge of the spot weld.     

A switchable cantilver for a chemically sensitive scanning force microscope

We describe a cantilever device for a novel ’Time-Of-Flight Scanning Force Microscope (TOF-SFM)’ concept that has the capability of chemical analysis. The cantilever device consists of a switchable cantilever (SC), a microfabricated extraction electrode, and a LEGO-type microstage, which combines two different systems. It allows quasi-simultaneous topographical and chemical imaging of a sample surface to be performed in the same way as with conventional scanning probe techniques. This is achieved by the micromachined SC with a bimorph actuator that provides a reasonable switching speed in comparison with mechanically operated switches. Secondly, a short tip-electrode distance to minimize the ions extraction voltage can be realized by LEGO-type microfabrication. The measured SC tip deflection is -100 μm at 35 mW, corresponding to an estimated heater temperature of -250°C. The maximum switching speed between the two modes is -10 msec, and the sensitivity ΔR/R of an integrated piezoresistive deflection sensor is -6.7× 10^-7/nm. The tip-electrode distance is only 10 μm. The TOF-SFM is currently integrated in an ultra-high-vacuum system to perform several measurements.     

Quality monitoring of resistance spot welding based on electrode displacement characteristics analysis

A new method is developed to monitor joint quality based on the information collection and process in spot welding. First, twelve parameters related to weld quality are mined from electrode displacement signal on the basis of different phases of nugget formation marked by simultaneous dynamic resistance signal. Second, through correlation analysis of the parameters and taking tensile-shear strength of the spot-welded joint as evaluation target, different characteristic parameters are reasonably selected. At the same time, linear regression, nonlinear regression and radial basis function (RBF) neural network models are set up to evaluate weld quality between the selected parameters and tensile-shear strength. Finally, the validity of the proposed models is certified. Results show that all of the models can be used to monitor joint quality. For the RBF neural network model, which is more effective for monitoring weld quality than the others, the average error validated is 2.88% and the maximal error validated is under 10%. __________ Translated from Chinese Journal of Mechanical Engineering, 2006, 42(10): 176–181 [译自: 机械工程学报]     

Effects on mechanical properties in electron beam welding of TC4 alloy by laser shock processing

The surface of TC4 titanium alloy welding line by electron beam welding (EBW) was processed by high power Q-switched and repetition-rate Nd: glass laser. Effects of laser power and spot diameter on residual stress and microhardness of the TC4 alloy welding line by laser shock processing (LSP) have been analyzed. Results show that residual stresses almost do not change as laser power is 45.9 J, spot diameter is ϕ9 mm; While laser power is 45.9 J, spot diameter less than ϕ3 mm, the distribution of residual stress in welding line occurs obvious variation, which residual stress increase obviously with spot diameter decrease. When power density is bigger than 1.8 × 10¹⁰ W/cm², residual stresses of electron beam welding line occur change by LSP, which improve obviously residual stress distribution; while laser power is bigger than 1.2 × 10¹⁰ W/cm², the surface micro-hardness of electron beam welding line occurs change by LSP, which improve obviously micro-hardness distribution. Mechanical properties of TC4 titanium alloy welding line will be improved by LSP, which provides experimental foundation for further controlling the distributions of residual stress and micro-hardness during laser shock processing. __________ Translated from Journal of Jiangsu University (Natural Science), 2006, 27(3): 207–210 [译自: 江苏大学学报 (自然科学版)]     

6.5倍微小型可见光变焦光学系统设计

连续变焦光学系统在执法取证、森林防火、海洋搜救、道路交通、无人机侦察等领域有着广泛且必不可少的实际应用。为提高变焦系统的性能指标,并使系统小型化,通过Zemax光学设计软件反复优化计算,设计了焦距为2.68～17.5 mm、视场为4.7°～31°的变焦系统。整个系统由4组10片透镜组成,物镜的像方F数为2.15～3,MTF值在250 lp/mm时均大于0.25,畸变在4.5%以内,光学总长小于27 mm,总质量小于0.77 g,具有结构紧凑、体积小、重量轻、分辨率高、成像质量好等优点,是一款微小型的连续变焦光学系统。     

Tribological characteristics of polycrystalline Magnéli-type titanium dioxides

The results presented in this paper have clarified experimentally, that titania-based Magnéli-phases (Ti₄O₇/Ti₅O₉ and Ti₆O₁₁) with (121)-shear planes exhibit more anti-wear properties than lubricious (low-frictional) properties. The results for dry sliding indicate that the coefficients of friction lie in the range of 0.1–0.6 depending on sliding speed and ambient temperature. The COF decreased with increasing temperature (T= 22–800°C) and increasing sliding speed (υ= 1−6 m/s). The dry sliding wear rate was lowest for the Al₂O₃ at 1 m/s at 800°C with values of 1.7 × 10−8 and 6.4 × 10−8 mm³/N m, comparable to boundary/mixed lubrication, associated with a high dry frictional power loss of 30 W/mm². The running-in wear length and, more important, the wear rate decreased under oscillating sliding tests with increasing relative humidity. The contact pressure for high-/low-wear transition increased under oscillating sliding tests with increasing relative humidity. At room temperature and a relative humidity of 100% the steady-state wear rate under dry oscillating sliding for the couple Al₂O₃/Ti₄O₇–Ti₅O₉ was lower than 2 × 10−7 mm³/N m and therefore inferior to the resolution of the continuous wear measurement sensor. TEM of wear tracks from oscillating sliding revealed at room temperature a work-hardening as mechanism to explain the running-in behavior and the high wear resistance. The hydroxylation of titania surfaces favours the high-/low-wear transition. This revised version was published online in August 2006 with corrections to the Cover Date.     

一种自准直仪摄远物镜光学结构的设计

设计了一种采用波长为650nm的单色红光为光源,焦距为450mm,D/f′=1∶9.375,视场角2w=0.6°的摄远物镜,主要应用在自准直仪上,利用其筒长小于系统焦距的特点,可以使仪器的体积更加小巧,方便携带。摄远结构可校正系统的球差、彗差、色差、象散和场曲。采用波长为650nm的红光光源,所以不用考虑色差的因素。摄远结构筒长L与系统焦距f′之比控制在2/3~3/4之间,摄远比达到了0.54。MTF曲线也达到了衍射极限,可有效提高检测精度,仪器的测量范围在1.5m之内。最后推导出了通过修调正负镜组之间的间隔来对仪器的示值误差进行补偿公式。     

Measurements of temperature and flow fields with sub-millimeter spatial resolution using two-color laser induced fluorescence (LIF) and micro-particle image velocimetry (PIV)

Comprehensive measurements for velocity and temperature fields have been conducted. A Micro PIV 2-color LIF system have been setup to measure the buoyancy driven fields in a 1-mm heated channel with low Grashof-Prandtl numbers [86<GγωPγ< 301] Fluorescence microscopy is combmed with an MPIV system to obtain enough intensity images and clear pictures from nano-scale fluorescence particles The spatial resolution of the Micro PIV system is 75μm by 67 μm and error due to Brownian motion is estimated 1.05% Temperature measurements have achieved the 4 7 μm spatial resolution with relatively large data uncertainties the present experiment. The measurement uncertainties have been decreased down to less than ±1.0 C° when measurement resolution is equivalent to 76 μm Measured velocity and temperature fields will be compared with numerical results to examine the feasibility of development as a diagnostic technique     

Friction and Wear Characteristics of Haynes 25, 188, and 214 Superalloys Against Hastelloy X up to 540 <Emphasis Type="Bold">°</Emphasis>C

As demand for more power increases, compression ratios, and operating temperatures keep rising. High speeds combined with high temperatures make turbomachinery sealing applications even more challenging. In order to confirm sufficient service life material pairs should be tested under conditions similar to engine operating conditions. This study presents high temperature friction and wear characteristics of cobalt/nickel superalloys, Haynes 25 (51Co–10Ni–20Cr–15W), Haynes 188 (39Co–22Ni–22Cr–14W), and Haynes 214 (75Ni–16Cr–3Fe–0.5Mn) sheets when rubbed against Hastelloy X (47Ni–22Cr–18Fe–9Mo) pins. Tests are conducted at 25, 200, 400, and 540 °C with a validated custom design linear reciprocating tribometer. Sliding speed and sliding distance are 1 Hz and 1.2 km, respectively. Friction coefficients are calculated with friction force data acquired from a load cell. Wear coefficients are calculated through weight loss measurements. Results indicate that Haynes 25 (H25) has the lowest friction coefficients at all test temperatures. Above 400 °C, H25 and Haynes 188 (H188) exhibit the best wear resistance. Protective cobalt oxide layers are formed on the H25 and H188 at 540 °C in addition to nickel, chrome, and tungsten oxides. Although, it has better oxidation resistance, Haynes 214 has relatively higher wear rates than other tested materials especially at low temperatures. However, its wear performance improves beyond 200 °C.     

Optimization of welding current waveform for dissimilar material with DP590 and Al5052 by Delta-spot welding process

The automotive industry has a target goal to improve fuel consumption due to restricted exhaust gas regulation. For this reason, the applicability of lightweight material, Al alloys, Mg alloys is also being expanded. In this concept, high strength steel, DP590 and light alloy, AL5052 are joined in the right place of the car body. However, it is difficult to join to steel and aluminum by conventional fusion welding. Generally, in respect to dissimilar metal joining by fusion welding, intermetallic compound layer is formed at the joint interface, hot cracking is generated. In this study, the effect of the current waveform on the mechanical characteristics and microstructure in Delta spot welding process of dissimilar metal was investigated. As results, Intermetallic compound (IMC) layer was reduced from 2.355 μm to 1.09 μm by using Delta spot welding process; also the welding current range improved by 50% in the delta spot welding, higher than in the inverter resistance welding. To conclude, the delta spot welding process adopting the process tapes contributes to improving the welding quality for dissimilar metals (Al5052 and DP590) due to a decrease in IMC layer.