果蔬切丁机的优化设计

国内现有果蔬切丁机存在着加工的大果蔬丁(10 mm以上)断面明显不平整的问题,无法满足食品加工要求。通过对果蔬丁的加工原理进行分析,建立了果蔬丁断面的曲线方程。分析了影响果蔬丁断面质量的因素,获得现有切丁机所加工的大果蔬丁断面不平整的主要原因。通过对推进器与条刀间角速度比和条刀轴相对于滚筒的位置参数优化,获得果蔬切丁断面理想时的参数组合。样机性能试验表明:切出的15 mm×15 mm×15 mm和20 mm×20 mm×20 mm规格的马铃薯立方块形状规整,其相对偏差百分数分别为11.7%,12.7%,均小于15%,达到了预期目标。     

三维果蔬切制技术发展与问题分析

主要对三维果蔬切丁机的发展现状进行了综述,对国内外三维果蔬切丁机的多种结构进行归纳与总结,并对常用的三维果蔬切丁机的结构以及工作原理进行梳理与分析。通过对三维果蔬切丁机切丁断面形状偏差的分析,总结了目前三维果蔬切丁机发展中遇到的主要问题,并对现有的解决思路进行了梳理,并探讨了提高切片、丝和丁的作业精度的相关技术,为三维切丁机切丁质量提供技术指导。     

准三维针刺碳/碳复合材料拉伸试验几何构型比对研究

本文选取了2种轴向外形尺寸和3种径向外形尺寸的准三维针刺碳/碳复合材料试样,轴向和径向的第一种形状均有带加强片和不带加强片两种构型。对这7种构型进行了拉伸试验,并对试验测得的拉伸强度和拉伸模量的大小、分散性以及破坏模式等做了对比分析。结果表明,直条型150mm×15mm×6mm(夹持部位35mm×15mm)在所选轴向构型中最优,直条形150mm×15mm×10mm(夹持部位35mm×15mm)构型在所选径向构型中最优。     

大尺寸O形丁腈橡胶圈动密封性能测试分析

为研究大尺寸O形橡胶密封圈端面动密封性能,研制适应于大尺寸O形橡胶圈的动密封性能测试平台,测试水介质条件下绝对压力在15～600 kPa范围内O形橡胶密封圈端面动密封性能.基于正交试验设计,研究不同介质压力、压缩量(0.75～1.25 mm)和转速(5～50 r/min)下内径600 mm(截面直径10 mm)的丁腈橡...     

65Mn弹簧挡圈锻、焊新工艺

在100t轨道起重机生产中,有一种弹簧挡圈的材质是65Mn钢,调质HRC40～45,外形主尺寸φ272×5(mm)数量12件/台,见图1。传统加工是把坯料锻制成φ280×130(mm)实心棒料,车削φ272外圆,钻φ242孔,用切刀切成一片片5mm厚的圆环,再进行铣、钻、热处理、磨削加工,最后由钳工切口。钻制φ242孔,不仅加工困难,且浪费材料和工时。对工艺革新后,用φ75圆棒锻制成25×50(mm)的矩形毛坯,再围成外径为φ280,内     

П形件多工位冲模的设计

有弯曲工艺的多工位连续式复合模可以连续冲制形状复杂的弯曲件，是结构较复杂、设计难度较大的一种多工位连续模。本文介绍两套П形弯曲件多工位连续式复合模典型结构及设计与计算方法，供参考。一、弯曲件多工位冲模设计1．工位安排及排样图设计（见图1排样图）从图1冲件图可知，其结构形状与尺寸，该冲件冲压工艺为：（1）冲孔：20mm2孔及小2．5mm中心底孔；（2）切角：端头四角倒6×45°角，（3）切槽口：底部中心孔两边3．5×9mm半圆槽口；（4）弯П形：弯脚长×宽＝29×26mm两边全等。接冲件图绘出的展开毛坯图后可以看出，20mm孔达距…     

巧用6m旋风铣床加工10m丝杠螺纹

我公司承接了一批10m滚珠丝杠合同,规格为100mm×10mm×9360mm×9800mm,用户要求在60天内先交付两副,交货周期短,加工难度大。当时我公司现场仅有6m旋风铣床一台,10m螺纹磨床一台。若按常规磨制方法来加工,一副丝杠粗开、半精磨、精磨就要花费20天以上时间,根本满足不了交货期要求。     

基于磁隙式吸附机构的槽车清洗机器人

给出了一种基于磁隙式吸附机构的槽车清洗机器人机构设计方案,采用磁隙式吸附装置平衡清洗作业过程中高压水枪反向冲击力产生的倾覆扭矩,提高系统稳定性裕度。建立数学模型描述清洗作业力学行为,利用有限元仿真优化磁吸附模块设计参数,计算不同气隙高度下单个磁吸附装置产生的吸附力。根据仿真结果,当采用2块40 mm×40 mm×15 mm与2块80 mm×40 mm×15 mm的永磁铁,磁铁间隙为10 mm,轭铁厚度为9 mm,气隙高度为10 mm时,单个磁吸附装置能够产生693 N的吸附力,槽车清洗机器人能够在20 MPa的清洗水压下稳定地工作。     

砖坯自动切条机构的优化设计

本文剖析了现有砖坯自动切条机存在的切截面形状不规整问题,利用偏心齿轮变速角位移的传动机构,使切割钢丝达到与泥条水平送进近似同步,从而找到了使砖坯切割面呈铅直平面型的可能途径。将所述理论应用于砖坯回转钢丝弓型自动切条机构设计,借助于正交设计优化法,达到了要求。     

基于厚膜工艺的微型FAIMS生化气体传感器设计

据高场非对称波形离子迁移谱(high-field asymmetric waveform ion mobility spectrometry,FAIMS)原理,设计了一种微型生化气体传感器。在大气压环境下,采用波长116.5 nm、电离能为10.6 e V真空紫外灯离子源对样品进行电离。迁移管的制作采用厚膜工艺,将迁移区和检测区集成到了陶瓷芯片上,迁移区由上下两块平板电极构成,尺寸为20 mm×10 mm×0.45 mm;检测区尺寸为8 mm×10 mm×0.45 mm。搭建了相应的FAIMS外围检测平台,以丙酮和甲苯为样品进行实验,通过高场非对称波形离子迁移谱技术进行传感器的性能验证实验,实验得到了它们的FIAMS谱图,表明所设计的基于FAIMS原理的气体传感器可以实现离子分离和过滤功能。     

Dicing of hard and brittle materials with on-machine laser-dressed metal-bonded diamond blades

The ultra-precision dicing of hard and brittle materials causes high wear on the abrasive tool which results in the deterioration of blade cross section as well as the decrease of diamond grain exposure. Resin-bonded diamond blades are used due to their in-process self-sharpening capability. Nevertheless, the shape of the blade cross section generated by self-sharpening is random which leads to poor accuracy when precise grooves need to be produced. Metal-bonded diamond blades feature higher tool lifetime and shape accuracy compared to resin-bonded blades, but are not capable of performing self-sharpening. In this study, the laser dressing of metal-bonded diamond blades is investigated to enable their use in the ultra-precision dicing of hard and brittle materials by continuous laser dressing. We investigated laser dressing with and without the presence of cooling water. The sharpness (grain exposure) after dressing is measured by the cutting face surface roughness. The dicing performance is evaluated by observing the dicing results in terms of cutting depth consistency and by monitoring the spindle power during dicing. Dicing blades which have been laser dressed in an environment with coolant feature less grain exposure than dicing blades which have been laser dressed in dry condition. The dicing results show an improvement in the sharpness and durability of laser-dressed dicing blades in comparison with new or conventionally dressed blades. The ability to apply and perform laser dressing on a dicing machine in an environment with coolant shows the feasibility of laser technology for continuous dressing.     

Out-of-plane neural microelectrode arrays fabrication using conventional blade dicing

This paper describes an optimized out-of-plane fabrication method for neural 3D high-aspect-ratio microelectrode array (MEA) based on a dicing technology platform (a standard procedure in semiconductor industry). The proposed MEA fabrication required important modifications in the dicing process. Since electrodes length reaches up to 4 mm, the main hindrance was the 2 mm cutting depth limit allowed for dicing machines with regular blades. This new procedure consisted on modifying Z-axis calibration, so cuts as deep as the exposure of blades were possible. The employment of proper blades for each fabrication step was also mandatory. Thin and high-exposure blades were used for deep cuts in silicon wafers, and V-shaped blades were employed to produce sharpened tips on the electrodes. Moreover, parameters as very low-cut speeds were essential to avoid wafer chipping and microcracks. Results showed high-precision and high-quality cuts in all steps of the 3D MEA fabrication, without unnecessary additional steps of etching post-processing. The optimized fabrication process was successfully demonstrated with a 3D neural probe array comprising 36 individually addressable electrodes.     

大型船用螺旋桨桨毂粗加工刀具路径规划研究

针对大型船用螺旋桨毛坯余量较大,相邻桨叶间存在重叠区,现有加工方法吊装复杂、需要二次装夹且叶根桨毂加工周期长等问题,提出了一种多轴对称加工叶根桨毂方案,并依据加工方案,应用定轴加工方法研究桨毂粗加工刀具路径规划.根据桨毂曲面特征,计算走刀行距与步长;基于定向包围盒(Oriented Bounding Box,OBB)干...     

Design and accuracy analysis of a metamorphic CNC flame cutting machine for ship manufacturing

The current research of processing large size fabrication holes on complex spatial curved surface mainly focuses on the CNC flame cutting machines design for ship hull of ship manufacturing. However, the existing machines cannot meet the continuous cutting requirements with variable pass conditions through their fixed configuration, and cannot realize high-precision processing as the accuracy theory is not studied adequately. This paper deals with structure design and accuracy prediction technology of novel machine tools for solving the problem of continuous and high-precision cutting. The needed variable trajectory and variable pose kinematic characteristics of non-contact cutting tool are figured out and a metamorphic CNC flame cutting machine designed through metamorphic principle is presented. To analyze kinematic accuracy of the machine, models of joint clearances, manufacturing tolerances and errors in the input variables and error models considering the combined effects are derived based on screw theory after establishing ideal kinematic models. Numerical simulations, processing experiment and trajectory tracking experiment are conducted relative to an eccentric hole with bevels on cylindrical surface respectively. The results of cutting pass contour and kinematic error interval which the position error is from –0.975 mm to +0.628 mm and orientation error is from –0.01 rad to +0.01 rad indicate that the developed machine can complete cutting process continuously and effectively, and the established kinematic error models are effective although the interval is within a ‘large' range. It also shows the matching property between metamorphic principle and variable working tasks, and the mapping correlation between original designing parameters and kinematic errors of machines. This research develops a metamorphic CNC flame cutting machine and establishes kinematic error models for accuracy analysis of machine tools.     

Some observations on knife properties and sectioning mechanics during ultramicrotomy of plastic embedding media

The edge and the trough surface of ultramicrotome glass knives were studied by interference light microscopy and electron microscopy. Particular attention was paid to the region which is commonly used for microtomy; here the bevel angle was calculated to 50–55°. The edge was serrated, even in the region used for sectioning, where the indentations measured up to 20 nm in depth. The imprints of edge serrations left on the sectioned material (Vestopal) were studied by electron microscopy. Different embedding materials displayed different degrees of compression when sectioned in the ultramicrotome: with Epon the compression was less than 10%, whereas methacrylate was compressed by more than 30%. Different trough fluids were tested: aqueous solutions of ethanol, acetone and dioxane gave less compression than pure water. However, the compression could also be reduced by exposing compressed Vestopal sections to these solutions. The direction and magnitude of the cutting force was measured with transducers during the sectioning of Vestopal blocks. Thus ～0·3 μm wide sections cut at a feeding rate of 80 nm and a speed of 2 mm/sec required a cutting force of about 8 mN. The direction of the forces was 8–15° from the plane of cutting.     

大口径油气管道坡口加工机床研制及其关键技术研究

建设中的中俄东线天然气管道工程在国内首次采用了φ1422 mm×80 mm钢管,最薄壁厚21.4 mm。详细介绍了φ1422 mm超大口径油气管道钢管坡口成型加工机床设计的技术方案,分析了保证坡口加工精度在设计过程中所采取的多项关键技术,提出了一体式定位、夹紧同步技术及浮动式切削技术,保证了坡口加工过程中的机床定位精度和切削精度。通过工程现场应用表明,该机床设计合理,运行性能平稳。     

Tungsten coating--a method of improving glass microtome knives for cutting ultrathin sections.

Glass knives for ultramicrotomy were considerably improved by coating the cutting edge with a film of evaporated tungsten metal. Knives treated by this method gave up to tem times as many acceptable sections as uncoated glass knives. They could also cut thinner sections and harder tissues than ordinary glass knives, and eliminated some of the cutting artefacts produced by them. No explanation for this improvement was found although several possibilities were examined.     

基于免形状测量模式的复杂形状测量机设计

为了高精度高效率地测量数学模型未知的复杂几何形状,介绍了"免形状测量模式",分析了该测量模式对仪器的基本要求,基于该模式设计了一台移动工作台式测量机。测量机以直线电机为驱动元件,以高精度长光栅为测量元件。为减小被测件重量对测量机的影响,设计了封闭式真空负压的空气静压气浮导轨和共平面的H形二维结构。设计了具有制动功能的Z轴和气浮隔振等关键部件。仪器量程为300 mm×300 mm×300 mm,测量不确定度为1.8μm,能测量数学模型未知的复杂几何形状。     

Characterization of the cutting edge of glass and diamond knives for ultramicrotomy by scanning force microscopy using cantilevers with a defined tip geometry. Part II

The cutting edge of glass as well as diamond knives was studied at high resolution using a scanning force microscope (SFM). The local shape of the cutting edge was estimated from single line profiles of the SFM topographs taking into account the exact shape of the probing tip estimated by a high‐resolution field emission scanning electron microscope (FESEM). The glass knives were prepared by ‘balanced breaking’. The radius of the investigated cutting edges was found to be 3.2–4.4 nm and 4.3–6.0 nm for the 35° and 45° diamond knife, respectively, and 3.4–4.3 nm for the glass knives. Besides the opening angle and the cutting edge radius, the friction of a knife during sectioning represents a significant factor influencing the quality of sections. Thus, the roughness of both the diamond clearance angle side and the back side was characterized as well. Corresponding RMS values of the roughness were found to be smaller on the back side (≈ 0.14 nm) than on the clearance angle side (≈ 0.26 nm).     

铸坯在线火焰切割小车设计

分析了铸坯切割机理,对火焰切割小车切割与冷却装置、夹紧与进给装置、在线切割系统等进行了设计,构建了铸坯在线切割小车控制系统,满足了铸坯在线切割的要求.该结构紧凑,切口平整,金属耗损少,能切割220mm以上方铸坯,铸坯火焰切割机寿命长.