蜂窝夹套结构焊接接头的应力强度分析

由于蜂窝夹套焊缝受力情况比较复杂,焊接部位经常出现焊缝开裂引起泄漏,焊接残余应力是重要的影响因素之一。运用大型有限元分析软件ABAQUS的热一力耦合功能,对304不锈钢蜂窝夹套的塞焊和填角焊两种焊接方式进行有限元模拟,得到了这两种焊接接头的残余应力分布情况。结果表明,塞焊焊接方式的蜂窝夹套焊缝处的残余应力大于采用填角焊方式的。采用塞焊方式蜂窝孔处的焊接残余应力较高,焊完第二个蜂窝孔后对第一个蜂窝孔的残余应力影响较大。而采用填角焊方式则这种影响较小。对塞焊和填角焊焊缝进行强度计算,结果表明填角焊焊缝的承载能力较好。研究结果为蜂窝夹套进行分析设计和控制焊缝开裂提供了理论基础。     

A high efficiency electrochemical machining method of blisk channels

This paper presents an electrochemical machining method in which three stainless steel tubes as cathode tools move towards workpiece parts with space trajectories and electrolyte is ejected from the outlets of the tool tube walls to the workpiece to electrochemically produce three blisk channels simultaneously. The shape and structures of cathode tool tubes are optimized numerically and experimentally for distributing the electrolyte flow more uniformly. A special experimental system with synchronous motion of three tool tubes has been developed. Experimental results indicate that three channels can be produced at one time with good quality and high efficiency.     

钢管无凹模冲孔凸模结构设计与优化

对钢管无凹模冲孔进行了实验研究,分别采用平凸模、凹凸模、尖凸模和斜凸模对圆钢管进行冲孔,分析了钢管无凹模冲孔时孔缘变形量的大小与凸模形式间的关系,提出了最佳凸模形状设计。实践证明:优化后的凸模在很大程度上减小了凹坑的塌陷量,提高了产品质量。     

Ⅴ型发动机气门挺杆孔加工组合机床设计

针对曲轴箱上挺杆孔直径小、位置深、尺寸精度高,各孔加工精度相同等特点,设计了工序比较集中的三工位钻扩铰组合机床,利用三工位转塔头实现钻、扩、铰三工步的转换,节约生产成本,避免定位误差;利用一套夹具装置对工件实行一次快速定位夹紧,避免了工件的重复定位误差;采用悬挂式活动钻模板,解决了细长刀杆刚度不足问题和刀具的定位、导向问题。利用该机床可实现工件快速装卸和可靠定位夹紧,可自动完成三个工位的工作循环,劳动强度低,生产效率高。     

负压式气浮平台供气压力的研究

液晶平板在线检测过程中,使用负压式气浮系统的稳定性更高,为了比较负压的大小对气膜稳定性、供气参数、质量流量的影响,运用气体润滑理论,对气浮平台的单个节流孔进行理论分析,得到气膜平面的压力分布规律。建立正负压节流孔间隔排布的通孔阵列模型,通过Gambit建立模型并划分网格,对模型提供不同的负压,导入Fluent进行数值计算,得到各种情况下通孔阵列和阵列中心的压力、速度分布曲线。比较得到负压为-2 k Pa时,气膜稳定性更好。分析不同负压所需与之匹配的正压,得到对同一支承物,气膜厚度不变的情况下,正压随负压的变化规律。最后从稳定性和经济性因素出发,得到玻璃光学检测仪器的气浮支承平台的供气参数。     

Use of micro ultrasonic vibration lapping to enhance the precision of microholes drilled by micro electro-discharge machining

In microhole machining of metal, micro electro-discharge machining (MEDM) is an effective method that can easily create a hole with a diameter under 100 μm. Due to the poor surface quality and shape of MEDM, a machining method that compounds MEDM and micro ultrasonic vibration lapping (MUVL) is proposed here to allow the production of high precision microholes with high aspect ratios. In our investigations, first, a circular or stepped circular microtool was made by the MEDM process, and the tool was used to create a microhole on a small piece of titanium plate in the same machining process. Finally, the abrasive particles driven by the same tool were utilized to grind this hole in the MUVL procedure, and a hole with a diameter about 100 μm can be obtained. Owing to the microtool and workpiece not taking apart from the clamping apparatus during different machining steps, the microhole was processed in the co-axial situation, so the precise shape and perfect surface can be obtained easily. For example, the diameter variation between the entrances and exits of the microholes could reach a value of about 5 μm when the workpiece had a thickness of 500 μm, if the circular microtools was used. Meanwhile, the roundness of the microholes clearly improved, regardless of whether circular or stepped tools were used. However, owing to the perfect grinding effect between the microholes and microtools, the stepped circular tools produced high quality surfaces more easily than the circular tools.     

微小凹坑阵列的电解转印加工试验研究

研究表明,合理的表面织构可改善活塞汽缸中摩擦副的润滑特性,提高抗磨减摩性能.试验了用电解转印法加工凹坑阵列,对加工中阴阳极之间的封闭区域建立数学模型,并进行了ANSYS电场分析.试验研究了阴极掩模胶膜厚度、加工间隙、加工电压对微坑形貌的影响,通过优化加工参数,提高了微小凹坑阵列的均匀性与微坑加工精度.采用光刻工艺制备了直径为10 μm、厚度为40 μm的阴极掩模,以此进行电解转印加工,可获得平均直径为140 μm、深度为30 μm的凹坑阵列.     

Improvement of hole exit accuracy in electrochemical drilling by applying a potential difference between an auxiliary electrode and the anode

Electrochemical drilling (ECD) is a promising and low-cost process for yielding multiple holes simultaneously in difficult-to-machine materials. In this process, the hole exit accuracy is very sensitive to the electrode feeding depth. In practice, excessive electrode feeding is necessary to ensure that all holes are drilled through simultaneously when there is an error in thickness of the workpiece plate. This results in stray removal at the hole exit and an etched and pitted surface. In the modification of ECD described here, a potential difference is introduced via an insoluble platinum auxiliary electrode that is attached beneath a dielectric perforated plate and arranged opposite to the hole exits to diminish the damage from the stray current and thereby improve the tolerance of the exit accuracy to excessive electrode feeding. Simulation results indicate that an appropriate value of the potential difference concentrates the current at the tool tip and may reverse the current direction on the workpiece surface. Experiments verify that this approach is effective in obtaining holes with good exit accuracy in the case of excessive electrode feeding. Furthermore, it is confirmed that this method is capable of drilling multiple holes with remarkably enhanced exit accuracy and uniformity.     

径向进给射流电解车削圆柱表面试验

径向进给射流电解车削加工是针对难加工材料回转体零件表面特征,利用电解液从阴极刀具内部喷向工件,刀具沿径向逐渐向工件进给进行电化学溶解的加工方法。通过流场仿真,优选出阴极刀具结构,利用10%的NaNO3溶液对316L不锈钢材料圆柱表面进行试验研究,分析平衡间隙、加工电压、工件转速、电解液压力对材料去除率和工件表面粗糙度的影响。结果表明:利用优选的刀具,对直径20 mm、高度10 mm的316L不锈钢圆柱表面径向单边车削0.5 mm,材料去除率可达0.391 g/min,表面粗糙度Ra<0.2μm。     

微细阵列孔的电解加工精度研究

从电解加工的特点出发,对影响微细阵列孔加工精度的因素进行了分析.电解加工过程中,工具阴极和工件阳极之间存在加工间隙是导致误差的根源.微细阵列孔的电解加工误差可分为复制误差和重复误差,电场强度的分布状态和杂散腐蚀是造成复制误差的最重要因素,而气泡在加工区域的堆积导致了重复误差的产生.通过理论和实验分析,为实验加工提供了提高加工精度的措施和办法.     

单工步与三工步无飞边冲孔工艺的对比研究

研究了一种单工步无飞边冲孔工艺，对该工艺与三工步无飞边冲孔工艺进行了对比研究，其模具结构简单，操作方便，制造精度及费用低，孔剪切口光洁剪切带长度达到材料厚度的80％，提高了孔的尺寸及形位精度，在工程生产中具有很高的实际应用价值。     

基于Dynaform的飞机封严板压窝成形工艺分析与优化设计

飞机封严板在敲制成形沉头窝孔后,表面出现不同程度的起皱变形问题,且难以消除.采用非线性有限元分析软件Dynaform对飞机封严板窝孔成形过程进行数值模拟.经研究分析发现,成形过程中由于封严板没有压边支撑,且成形方式过于粗糙剧烈,导致封严板起皱变形.针对这些问题制定了相应措施,改变以往的敲窝成形方法,发明了一种气动压窝器...     

A new through-feed centerless grinding technique using a surface grinder

This paper proposes an alternative centerless grinding technique, i.e., through-feed centerless grinding using a surface grinder. In the new method, a compact centerless grinding unit, composed of a guide plate, an ultrasonic shoe, a blade, and their respective holders, is installed onto the worktable of a surface grinder, and the through-feed centerless grinding operation is performed as the workpiece located on the guide plate is fed into the space between the grinding wheel and ultrasonic shoe. The ultrasonic shoe, produced by bonding a piezoelectric ceramic device onto a metal elastic body, is tilted at a small angle so as to provide sufficient force to control the workpiece rotational motion and to feed the workpiece along its axis by the ultrasonic elliptic-vibration. In this paper, the workpiece motion control tests were carried out firstly to make sure that the workpiece rotational speed and through-feed rate can be exactly controlled by the ultrasonic shoe which is essential for performing high-precision grinding operations. Then, the effects of major process parameters such as the workpiece eccentric angle, the stock removal, the ultrasonic shoe tilt angle and the applied voltage amplitude on the machining accuracy (i.e. workpiece cylindricity and workpiece roundness) were clarified experimentally. The obtained results indicate that: (1) the workpiece rotational speed can be adjusted by changing the applied voltage amplitude, whereas its through-feed rate can be adjusted by changing both the applied voltage amplitude and the ultrasonic shoe tilt angle; (2) the optimum eccentric angle is 6°, and a larger stock removal, a smaller tilt angle, or a higher applied voltage is better for higher machining accuracy; (3) the workpiece cylindricity and roundness were improved from the initial value of 16.63 μm and 14.86 μm to the final ones of 1.49 μm and 0.74 μm under the optimal grinding conditions.     

高速列车安装板多工位级进模设计

高速列车安装板外形尺寸为275.3 mm×112.5 mm×29.5 mm,其弯曲部分为不规则Z字形,Z字形结构由2个方孔、1个圆孔和1个腰形孔组成,中间设有1条补强筋。根据安装板结构较为复杂的特点,对其成形工艺进行分析,在此基础上制定了3种冲压方案,经过对比分析,最终确定采用9个工位级进模成形制件,并确定了制件压筋预成形整形的排样方案。依次介绍了安装板模具的整体结构设计、模具预成形结构设计和模具成形工序结构设计。冲压成形工艺试验表明,安装板多工位级进模结构设计合理,其中采用预成形工艺能很好地克服制件回弹问题,满足制件大批量生产的需要。     

侧柱加强板斜刃切断模的设计

铁路货车用侧柱加强板是典型的中厚板长大冲压件,材质为Q450NQR1,在理论分析的基础上,优化设计了冲压工艺方案,可以提高侧柱加强板零件的使用性能和加工可行性,并详细介绍了该斜刃切断模的结构和工作过程.经生产实际验证,模具操作简便、安全可靠,产品质量合格,模具已生产数万件产品,经济效益显著.     

辅助阳极在电弧离子镀和磁控溅射技术中的应用和研究进展

按照位置分类,概述了3类辅助阳极。第1类布置在阴极附近,能起到吸引电子,增大离化率,并降低沉积温度的效果,同时若有带负电的离子,也会被吸引至阳极;第2类布置在基片的背面,在吸引电子达到阳极的过程中,会增大基片附近工艺气体和沉积物的离化率,正离子在负偏压的引导下会和基底发生碰撞,达到基底活化或者提高膜层质量的目的;第3类为特殊工件类,如管内壁镀膜时通过辅助阳极的布置,提高管腔内等离子体的均匀性,从而增加膜层厚度和质量的一致性。辅助阳极的增加只需在真空室特定位置布置特定形状的阳极即可,即使需要额外引线,只需一个接线法兰口就能完成,非常方便。辅助阳极加载的正电压一般在0至几百伏之间,如果是0,则直接和真空腔室连接即可,必要时串联电阻。辅助阳极技术具有改变离子能量和方向的特点,能起到对大颗粒的抑制作用,能改变到达膜层表面离子的能量,对膜层质量的提高具有重要意义,值得推广。     

型孔电解加工阴极优化试验研究

为解决电解加工型孔的加工稳定性和形状精度等问题,建立了异形孔电解加工稳定过程中加工间隙数学模型,分析了工具阴极结构对加工区域和非加工区域的电场及其均匀性以及其对电流密度与加工效果的影响,通过优化工件结构改善了加工间隙内的电场分布,使工件形状精度显著提高,并进行相关试验对仿真结果进行验证。得出结论:在相同的电解加工参数下,工具电极的结构对工件的形状精度有着显著的影响,通过优化工具电极结构,改善加工间隙内的电场分布与电流密度,让加工间隙内的流场更为稳定,使工件侧壁垂直度提高,提高了电解加工的形状精度与加工稳定性。     

Numerical study of electrode geometry effects on resistance spot welding

Abstract

This work numerically investigates the geometrical effects of the electrode containing a coolant hole on transport variables during resistance spot welding. The model accounts for transient magneto-fluid mechanics, heat and species transport, bulk resistance in workpiece, and film and constriction resistances at contact interfaces. The computed results show that electrode cooling due to the coolant hole influences transport processes during not only freezing and cooling periods but also heating and melting periods. Electrode cooling can be interpreted by thermal resistance, depending on the shapes of the electrode and coolant hole within the growing thermal diffusion layer. Major factors affecting electrode cooling are different in distinct time stages. In most cases, enhanced electrode cooling due to the coolant hole decreases the electrode temperature and nugget growth rate. A decrease in the electrode face radius strongly increases nugget growth rate and workpiece temperature and decreases electrode temperature, whereas its effect on cooling rate is insignificant. The optimum design and sensitivity analysis of the electrode shapes subject to required cooling rate, nugget growth rate and welding time are revealed.     

基于视觉定位的玻璃基板切割生产设备的设计

微电子用玻璃基板加工过程中需要将来料的大板玻璃切割分断成小板,以往采用机械定位的方式,通过定位治具与工件进行机械接触,工件的侧边受到定位治具的压力,易发生形变或者因外力产生崩口或裂痕等缺陷,良品率较低。针对上述问题,设计了基于视觉定位的玻璃基板切割分断生产设备,论述了玻璃基板切割分断机构设计的整体方案、结构组成、视觉定位系统的功能及控制流程。上料搬运、切割和分断过程中分别采用线阵相机识别系统进行初对位和自动对位,减少了单片玻璃的边破和角破,提高了单片玻璃的边缘质量。     

纯铜浇注铜阳极模铸件的裂纹及气孔浅析

采用感应电炉熔化高纯阴极铜,铸造浇注阳极板用铜阳极模铸件,对试验过程中阳极模的裂纹和气孔的生成机理及影响因素等进行了分析,并提出了预防和改进措施,为浇注铜阳极模铸件生产提供了借鉴和参考。