基于弹流润滑的一种减磨方法

良好的润滑状态所形成的润滑油膜可以有效避免两接触面直接接触而造成磨损,但是由于一些高副接触表面的润滑油膜比较稀薄,零件磨损还是非常严重.提出一种可以增大高副接触表面的油膜厚度,改善接触表面润滑效果的新方法,即在零件表面制造大量排列有序的微深孔.通过理论分析和试验验证了零件表面具有微深孔时可以增大接触面的油膜厚度,降低油膜压力,提高零件的耐磨性.     

硬质合金双轮深孔滚压工具

在我厂生产的产品零件中,大小油缸的加工精度和表面光洁度,技术要求都比较高。特别对深孔零件的加工,成为技术关键。为了解决这一技术难题,曾采用过“可调式双轮内孔滚压工具”。由于滚轮材料系高速钢制成,耐     

硬质合金双轮深孔滚压工具

在我厂生产的产品零件中,大小油缸的加工精度和表面光洁度,技术要求都比较高。特别对深孔零件的加工,成为技术关键。为了解决这一技术难题,曾采用过“可调式双轮内孔滚压工具”。由于滚轮材料系高速钢制成,耐磨性较差,所以影响了工具的使用寿命。针对这个问题,又试制了“硬质合金双轮深孔滚压工具”。经使用证明,在加工长为2600毫米,孔径为180毫米的深孔油缸时,其表面光洁度由原始的▽5提高到▽8～▽10,不仅获得了较高的表面光洁度和表面     

精密偏心深孔加工工艺

我们在承接外协任务中,就碰到需要加工高精度偏心深孔问题。经过实践,采用常规方法,成功地加工出了合格的零件。一、零件结构及技术要求图1是被加工零件简图。零件材料为40Cr调质,需要加工(?)16.6_0~(0.025)mm偏心孔,孔深463mm,表面粗糙度R_a0.8μm。孔轴心线对零件中心线平行度0.03mm,中心距38.83_0~(0.05)mm。因此,精密深孔的加工与保证偏心距的尺寸、形位公差就构成了此种零件特殊的工艺要求。     

CA6140杠杆加工工艺分析

CA6140杠杆零件起支承、固定作用的,其主要加工面是平面及孔;遵循先面后孔的加工原则,以杠杆Φ45 mm外圆面作为粗基准,以Φ25 mm孔及其下表面作为精基准,确定了工艺路线,每一道工序又分为粗加工和精加工工步,确定各工步的加工余量,保证加工精度;选用组合机床和专用及组合夹具以实现零件的加工工艺过程,为后续工艺过程的实施提供理论依据。     

高副接触机械零件弹流动力润滑研究新进展

弹性流体动力润滑是润滑理论的一个重要分支,也是关系到高副接触机械零件使用耐久性和可靠性的关键技术问题。计算机模拟仿真技术、数值计算方法和弹流测试技术的发展,推动了弹流润滑理论的发展和该理论在高副零件摩擦副设计中的广泛应用。综述齿轮、凸轮、轴承3种高副接触零件基于表面粗糙纹理、轮齿修形、有限长接触、热效应、镀层等因素的弹流润滑研究发展概况。指出现代弹流润滑理论虽然在高副接触零件中的应用已逐渐接近工程实际要求,能够较可靠地解决实际工况下的润滑难题,但在非稳态效应和真实粗糙表面对高副零件弹流润滑的影响方面,高副零件弹流润滑的多重参数耦合、计算机仿真及相关实验验证方面,还须进一步深入研究。     

高精度深孔表面粗糙度检测仪

针对测量领域深孔表面粗糙度测量存在的问题，研制了一种便携式微控表面粗糙度检测仪。主要用于孔径Φ38以上深孔管件内孔表面粗糙度的测量，测孔深度可达18m．既可应用于石油泵管内孔表面粗糙度测量，也可应用于其他深孔管件的内孔表面粗糙度测量。仪器质量轻，操作简便，便于携带，是深孔加工行业质量检测部门的实用计量、检测仪器。     

轻气炮身管深孔加工工艺研究

针对某轻气炮身管的零件结构和材料特性,分析难加工深孔零件的加工难点,确定合理的加工工艺。通过试验,优选刀具材料和切削参数。从工装设计方面,采用保护架和弹性厚壁套等措施解决难加工深孔零件的加工变形。根据孔轴线偏斜影响因素分析,提出通过附加外力控制孔轴线偏斜量的方法。结果表明:采用该工艺加工身管,内径尺寸精度和表面粗糙度均达到相应技术要求,孔轴线偏斜量为0.9mm/m,解决了难加工深孔零件的加工变形和孔轴线偏斜问题。     

改善机械零件表面形貌的实验研究

机械零件表面形貌对于它的润滑及抗擦伤性能有着重要的影响。近来，人们试图在已加工的机械零件表面，特别是高副零件（例如点、线接触的凸轮－挺杆）进行改造。激光微精处理是其中最有效的方法之一。ＳＲＶ试验表明，当激光微精处理参数选择得当时，可使试件表面的抗擦伤负荷有大幅度的提高（在常温和高温条件下）。这一结果标明激光微精处理技术在工业应用上将具有广阔的前景。     

Ti6Al4V钛合金枪钻加工轴线直线度误差试验研究

针对某大型飞机轴类零件深孔加工粗糙度差、轴线偏差和切屑不易控制等问题,进行了Ti6Al4V钛合金枪钻加工试验,测试了枪钻加工深孔的轴线偏差、孔径误差和加工表面完整性,并分析了产生偏差的主要原因。从而优化了Ti6Al4V钛合金枪钻加工工艺参数,得到了Ti6Al4V钛合金17深孔枪钻加工最佳工艺参数,最终实现了860mm深孔的枪钻加工,使得最终综合误差控制在0.2mm以内,表面粗糙度Ra小于1.6μm。     

电火花机床数控改造设计

针对硬质合金微深孔难加工的特点,采用将原有的电火花线切割机床改造为电火花磨削数控机床的方案,既保证了加工品质,提高了生产率,又比较经济,满足了生产的需要。     

脉冲宽度对激光打孔影响的试验研究

激光打孔是目前小孔加工中不可缺少而且应用广泛的加工方法,采用激光可以打出小至几微米的微孔。本文利用CO2激光器,选择不同的脉冲宽度分别对0.5 mm和1.0 mm 2种厚度的304不锈钢进行打孔试验,记录测量数据,利用ORIGIN软件进行数据处理,并得出曲线规律图,分析了脉冲宽度与小孔质量的关系。     

水射流辅助激光刻蚀Al2O3陶瓷的试验研究

设计了一套用于实验的水射流辅助激光刻蚀加工装置,将激光和介质射流冲蚀加工相结合,研究激光加工参数和射流加工参数对试样材料激光复合刻蚀量和截面质量的影响。实验结果表明,激光工艺参数和射流加工参数对工件加工表面的质量优劣有着决定性的影响;该复合加工工艺可以清除加工时产生的90%以上熔渣,能有效地降低材料表面粗糙度,使得加工出的盲孔成为较为规则的倒三角形。     

Experimental investigations and analytical modeling of multi-pass CO2 laser processing on PMMA

In this research work, microchannels have been fabricated utilizing multi-pass CO₂ laser processing on Poly-methyl meth-acrylate (PMMA) substrates. CO₂ laser engraving machines are cost effective and less time consuming compared to other tools and methods of fabricating microchannels on PMMA. However, the basic problem of low surface finish of the microchannel walls still restricts thus fabricated product from many potential applications. In this work, experimental and theoretical investigations of multi-pass CO₂ laser processing on PMMA have been conducted. A number of experiments were performed to establish the relationship between laser power and scanning speed with microchannel parameters like width, depth, heat affected zone, surface roughness and surface profiles. Experiments were conducted at four different power settings with 50 mm/s of constant scanning speed and seven numbers of passes in each setting. Changes in thermo-physical properties of PMMA were observed for as-received PMMA sample and PMMA sample residing in heat affected zone (HAZ) for first pass and secondary passes respectively. Effect of different numbers of passes on microchannel width, depth, HAZ and surface roughness were explored for different power setting. Microchannel profiles resulting from different numbers of passes have been compared. Energy dispersive X-ray analysis was performed to determine elemental composition after each pass. Many advantages of multi-pass processing over single-pass processing were recorded including high aspect ratio, low heat affected zone, smoother microchannel walls and reduced tapering of microchannels. An energy balance based simple analytical model was developed and validated with experimental results for predicting microchannel profiles on PMMA substrate in multi-pass processing. Multi-pass processing was found to be time and cost effective method for producing smooth microchannels on PMMA.     

液压支架激光熔覆不锈钢合金涂层的实验研究

采用激光熔覆技术在硅锰钢样件表面制备了不锈钢涂层,用SEM和能谱仪分析了基体与熔覆层界面以及熔覆层之间的微观组织及成分,开展了试样弯折和冲击强度测试实验。结果表明:在激光功率为6kW、扫描速度为8mm/s、光斑直径为5mm、搭接率30%的工艺条件下,基体与熔覆层界面以及熔覆层之间出现小亮带,形成冶金结合;熔覆方向垂直于观察面的覆层形貌呈蜂窝状,熔覆方向与观察面平行的覆层形貌呈竖直条状;在功率6kW、扫描速度16mm/s、光斑直径5mm、搭接率30%时,熔覆层与基体以及熔覆层之间会产生夹渣;熔覆层具有较好的韧性和冲击强度,熔覆后的试样的冲击强度提高了7.7%。     

Analysis of silicon via hole drilling for wafer level chip stacking by UV laser

For stacking wafers/dies, through-silicon-vias (TSVs) need to be created for electrical connection of each wafer/die, which enables better electrical characteristics and less footprints. And for via hole processing, chemical methods such as DRIE (Deep Reactive Ion Etching) are mostly used. These methods suffer the problems of slow processing speed, being environment-unfriendly and damage on the existing electric circuits due to high process temperature. Furthermore, masks are also needed. To find an alternative to the methods, researches on the laser drilling of via holes on silicon wafer are being conducted. This paper investigates the silicon via hole drilling process using laser beam. The percussion drilling method is used for this investigation. It is also examined how the laser parameters- laser power, pulse frequency, the number of laser pulses and the diameter of laser beam- have an influence on the drilling depth, the hole diameter and the quality of via holes. From these results, laser drilling process is optimized. The via hole made by UV laser on the crystal silicon wafer is 100μm deep, has the diameter of 27.2μm on the top, 12.9μm at the bottom. These diameters deviate from the target values by 2.8μm and 0.4μm respectively. These values correspond to the deviation from the target taper angle of the via hole by less than 1°. The processing speed of the laser via hole drilling is 114mm/sec, therefore, etching process can be replaced by this method, if the number of via holes on a wafer is smaller than 470,588. The ablation threshold fluence of silicon is also determined by a FEM model and is verified by experiment.     

Femtosecond laser-induced simultaneous surface texturing and crystallization of a-Si:H thin film: morphology study

Hydrogenated amorphous silicon (a-Si:H) thin films have been considered for use in solar cell applications because of their significantly reduced cost compared with crystalline bulk silicon; however, their overall efficiency and stability are less than that of their bulk crystalline counterparts. Limited work has been performed on solving the efficiency and stability issues of a-Si:H simultaneously. Surface texturing and crystallization on a-Si:H thin film can be achieved through one-step femtosecond laser processing, which can potentially alleviate the disadvantages of a-Si:H in solar cell applications. In this study, submicrometer conical and pillar-shaped spikes are fabricated by irradiating a-Si:H thin films deposited on glass substrates with hundreds of 800 nm-wavelength, 130 fs-duration laser pulses in air, and water environments, respectively. The formation mechanisms for the surface spikes are discussed, and the differences in the surface feature characteristics are also presented and explained within the context of the different processing environments. The effect of laser processing on light absorption and crystallinity will be studied later.     

氮稀释高效电激励连续波HF/DF化学激光器

提出使用低温吸附泵代替传统的机械真空泵和洗消装置的设想,以大幅降低电激励连续波HF/DF化学激光器的体积和重量.针对该技术需将常用的氦稀释剂替换为氮稀释剂从而引起激光器效率大幅下降的问题,对起音速阵列喷管激光器进行了研究.为提高氮稀释剂激光器效率,研制了周期4 mm间隔排列的狭缝一列孔超音速阵列喷管,以代替传统的单通道...     

利用曲面计算全息图进行非球面检测

研究了利用曲面计算全息图进行非球面检测.分析了曲面计算全息图的衍射特性,给出了曲面计算全息图与传统检测方法相结合检测凹非球面和凸非球面的原理及特点,并进行了具体设计.利用激光直接写入设备,在口径为110mm、曲率半径为504mm的曲面基底上制作出了计算全息图,并对金刚石车床车削的凸面非球面进行了检测.利用两步测量法解决了凸非球面的中心部位难以检测的难题,同时利用旋转相减法消除了调节误差,非球面的面形精度为234nm(P-V),与金刚石车床的精度相符.     

Finite Element Modeling of the Technology of Multiple Laser Shock Processing of Materials Using the Eigenstrain Method

The laser shock processing (LSP) of material is an efficient modern technology of processing of metal materials, during which significant compressive residual stresses contributing to an increase in their strength and tribological and operational characteristics are generated in the subsurface area. The finite element modeling of the technology of multiple laser shock processing is carried out using the eigenstrain method. The level of the compressive residual stresses arising under LSP is determined. It is shown that the residual stresses on the surface of the VT-6 alloy grow from 510 to 830MPa with an increase in the number of pulses from 1 to 4, and the depth of the zone of the compressive residual stresses increases respectively from 1.26 mm after the first pulse to 1.60 mm after the fourth pulse.