【摘 要】
：
In nanofluid minimum quantity lubrication(NMQL)milling of aviation aluminum alloy,it is the bottleneck problem to adjust the position parameters(target distance
【机 构】
：
School of Mechanical and Automotive Engineering,Qingdao University of Technology,Qingdao 266520,Chin
论文部分内容阅读
In nanofluid minimum quantity lubrication(NMQL)milling of aviation aluminum alloy,it is the bottleneck problem to adjust the position parameters(target distance,incidence angle,and elevation angle)of the nozzle to improve the surface roughness of milling,which has large and uncontrollable errors.In this paper,the influence law of milling cutter speed,helical angle,and cavity shape on the flow field around the milling cutter was studied,and the optimal nozzle pro-file parameters were obtained.Using 7050 aluminum alloy as the workpiece material,the milling experiment of the NMQL cavity was conducted by utilizing cottonseed oil-based Al2O3 nanofluid.Results show that the high velocity of the surrounding air flow field and the strong gas barrier could be attributed to high rotating velocities of the milling cutter.The incidence angle of the nozzle was consistent with the helical angle of the milling cutter,the target distance was appropriate at 25-30 mm,and the elevation angle was suitable at 60°-65°.The range and variance analyses of the signal-to-noise ratio of milling force and roughness were performed,and the chip morphology was observed and analyzed.The results show that the optimal combination of nozzle position parameters was the target distance of 30 mm,the incidence angle of 35°,and the elevation angle of 60°.Among these parameters,target distance had the largest impact on cutting performance with a contribution rate of more than 55％,followed by incidence angle and elevation contribution rate.Analysis by orthogonal experiment revealed that the nozzle position parameters were appropriate,and Ra(0.087 pm)was reduced by 30.4％from the maximum value(0.125 pm).Moreover,Rsm(0.05 mm)was minimum,which was 36％lower than that of the seventh group(Rsm = 0.078 mm).
其他文献
乳腺癌是全球女性发病率和死亡率最高的癌症。采用红外热成像技术能发现早期乳腺癌,并降低死亡率。借鉴了国内外的相关研究成果,采用冷环境及热电激发双重诱导下的红外热成像方法来解决小尺寸癌变组织和乳腺深部癌变组织的红外热成像应用效果差的问题。红外热成像的对比度显著增加了,且通电模式下的温度对比度提高了26.5%。研究表明,热对比度主要受癌变组织大小、深度和温度的影响,同时还受环境温度和换热系数的影响。通过同时控制环境和热源温度的措施提高了热对比度,预期乳腺癌的早期筛查效果可提高50%以上。
在中华五千年灿烂的诗文曲赋中,有种诗词没有诗经的风雅,没有唐诗、宋词、元曲的委婉,也没有当代诗歌的随意,但诗词的情怀却大义凛然,令人难忘。因为,诗词是蘸着信念和鲜血写就的。每次吟诵,这些诗句所蕴含的诗魂在眼前跳动。不,这不是诗,是一个个鲜活生命凝成的。
针对传统以经验为主的数控制造项目管理带来的资源冲突及工作滞后等问题,以某型号结构件数控制造项目管理为例,在制定初始进度计划和分析制造过程关键路径的基础上,采用关键链方法优化项目进度计划,并在实际生产中进行应用。结果表明,该方法能够避免资源浪费、进度拖延等现象,保证结构件交付节点,为飞机结构件数控制造项目进度安排探索了管理路径。
研究了InSb红外焦平面探测器的区域性过热盲元问题。通过故障分析以及有针对性的排查对比试验,排除了封装、胶水填充和划片等因素,并将故障定位在钝化工艺前。通过对钝化前的InSb材料片表面进行X射线光电子能谱测试,发现它含有Al和As等杂质元素,存在钝化前材料表面杂质含量较多的隐患。杂质元素在PN结的耗尽区形成杂质能级,加载电压后容易导致PN结漏电流较高,使I-V特性退化,从而形成过热盲元。通过缩短器具洗液的更换周期并且分隔使用多个生产线的器具,可以减少材料表面的杂质附着,使区域性过热盲元问题得到有效解决。
Ultrasonic vibration-assisted ELID(UVA-ELID)grinding is utilized as a novel and highly efficient processing method for hard and brittle materials such as cerami
为了提高军机复杂系统任务可靠性预计的准确性,弥补传统可靠性预计方法的不足,提出建立以任务失败为顶事件,以单元的输入端口功能失效状态和单元自身的失效状态为底事件的故障树方法,通过Saftylab、Rellab等评估软件在此基础上实现自动化的故障树生成并计算系统任务可靠性指标。
共青团是党联系青年的桥梁和纽带,是党的助手和后备军,是国有企业高质量发展的生力军.以内蒙古太平矿业有限公司党建带团建为例,分析了团员青年工作生活现状,确定了团员青年
风云四号A星干涉式大气垂直探测仪(Geostationary Interferometric Infrared Sounder,GIIRS)中波通道的最优选择是有效变分同化此资料的关键技术之一,能减少冗余信息所引起的变分同化和反演的不适定性。将通用的熵减法(Entropy Reduction,ER)用于GIIRS通道优选。此外,由于红外探测器观测容易受云影响,在变分同化GIIRS亮温资料时,需要进行云检测以获得晴空视场点或云参数信息。采用最小剩余法对GIIRS资料开展了云检测研究。该方法不仅能判识视场点是
花丝工艺是中国传统金银细工的代表性工艺之一,被列入第二批国家级非物质文化遗产名录,但该工艺存在生产效率低、技艺传承难、工艺质量不稳定等问题,限制了其批量化生产应用。试验分别采用传统手工制作、翻模铸造、3D打印等方式制作银花丝首饰,借助体视显微镜、扫描电镜等手段观察其工艺质量,并对比分析了艺术效果、生产效率和生产成本。结果表明:对比传统手工制作方式,采用手工制作或3D打印原版后翻模铸造机械化批量生产方式可明显提高花丝首饰的生产速度,降低生产成本,且在花丝纹样排列均匀性与材料适用范围等方面更有优势,但在花丝纹
In the manufacturing of thin wall components for aerospace industry,apart from the side wall contour error,the Remaining Bottom Thickness Error(RBTE)for the thi