A general framework for geometry design of indexing cam mechanism

Indexing cam mechanism is one of most important mechanisms in automated machineries. This paper presents a general frame for kinematic analysis and geometry design of indexing cam mechanism, such as parallel cam mechanism and roller gear cam mechanism. This method applied screw theory to describe structure of cam mechanism and developed the kinematic equations by using Product of Exponentials Formula (PEF). As long as such structure parameters are given as position and orientation of central line in turret, cam and rollers, geometry modeling of indexing cam can be implemented in a general frame of kinematic equations by applying this method. The paper gives examples to obtain the geometry models of roller gear cam, barrel indexing cam and parallel indexing cam. Our work suggests that this method can avoid the burdensome work on building coordinate systems, transformation matrix and understanding on the mechanism. Moreover, this method can be used to innovate and design new types of indexing mechanism.     

Analysis of gas foil bearings integrating FE top foil models

Gas foil bearings (GFBs) find widespread usage in oil-free turbo expanders, APUs, and micro gas turbines for distributed power due to their low drag friction and ability to tolerate high-level vibrations. The performance of GFBs depends largely on the support elastic structure, i.e. a smooth foil on top of bump strips. Conventional models include only the bumps as equivalent stiffnesses uniformly distributed around the bearing circumference. More complex finite element (FE) models couple the elastic deformations of the 2D shell or 1D beam-like top foil to the bump deflections as well as to the gas film hydrodynamics. Predictions of journal attitude angle and minimum film thickness for increasing static loads and two journal speeds are obtained for a GFB tested decades ago. For the GFB studied, 2D FE model predictions overestimate the minimum film thickness at the bearing centerline, while underestimating it at the bearing edges. Predictions from the 1D FE model compare best to the limited tests data, reproducing closely the experimental circumferential wavy-like film thickness profile. Predicted stiffness and damping coefficients versus excitation frequency show that the two FE models result in slightly lower direct stiffness and damping coefficients than those from the simple elastic foundation model.     

改善并粗条干CV值的体会

为了改善CJ 7.3 tex纱的并粗条干,对并条工序及粗纱工序的工艺进行优选,并条工序减小凹凸罗拉厚度、合理选择后区牵伸倍数和压力棒调节环大小,减小张力牵伸;粗纱工序优选喇叭口及隔距块大小,合理配置后区牵伸倍数,最终并条条干与粗纱条干得到改善,且成纱各项质量指标均有所改善.     

使用压力棒隔距块生产纯棉特细号纱的实践

分析了细纱机前牵伸区使用压力棒的作用和效果,在CJ 5.83 tex品种上采用罗拉隔距、后区牵伸倍数、钳口隔距3因素3水平正交试验对工艺进行了优选.结果表明:工艺配置为罗拉隔距19 mm×35 mm、后区牵伸1.17倍、钳口隔距2.5 mm时成纱质量较优.推广使用压力棒隔距块后.对条干CV、千米细节、千米粗节改善明显,但千米棉结略有增加.曲面形压力棒有助于减少须条上翻现象.在使用中要加强机台清洁,同时做好器材维修减少"出硬头".     

R40型转杯纺纱机纺针织纱的工艺优选

探讨R40型转杯纺纱机纺针织纱的工艺优化.通过对R40型转杯纺纱机纺针织纱时转杯直径、分梳辊速度、补风口位置及机械手参数设定进行试验和优选,并对转杯纱与环锭纱进行质量对比分析.指出:通过纺纱工艺的优化试验,正确配置转杯纺关键工艺参数,才能充分发挥进口设备的技术优势,生产出了满足用户需要的高质量的转杯纺针织纱.     

预负荷空心圆柱滚子轴承刚度分析

根据预负荷空心圆柱滚子轴承变形协调条件,建立了轴承内圈的平衡方程,运用卡氏定理确定了滚子的负荷和变形间的关系式,据此导出了预负荷空心圆柱滚子轴承的刚度计算公式,依据此公式对某型号轴承刚度进行分析研究,结果表明:预负荷空心圆柱滚子轴承的刚度与外载荷无关,且随着空心度的增大而减小,随着滚子个数的增加而增大。     

辊式板带矫直机压下量的计算和设定

在研究矫直辊间板带弯曲挠度的基础上,给出了压下调整量的计算方法,建立了基于反向弯曲挠度和弹复曲率计算弯曲力矩的方法,更便于考虑材料的强化和矫直机的型式及调整方案,对矫直机的设计和生产具有实际应用价值。     

顶吹烟化法在回收铟中的应用

顶吹烟化是一种在炼铅炉渣中有效回收铟的方法。通过热力学计算阐明了铅渣中铟的还原性与挥发性;同时,试验研究了还原温度和时间等因素对铅锌还原挥发率的影响。研究指出,温度、时间和炉渣中原始含锌量对烟化挥发铟有影响。结果表明,在煤的配入量为炉渣质量的50%、还原温度为l 250℃、时间为60 min的条件下,锌的挥发率高于83.67%,铟的挥发率高于60.67%,铅的挥发率高于92.14%。当原铅渣中锌含量达到8%时,铟挥发率可达90.27%。     

深天井钻机钻进导孔的工作参数研究

为了确保天井钻机在钻进导向孔时牙轮钻头处在岩石的有效体积破碎状态中工作,基于MATLAB软件,对大量深天井钻机钻进不同直径导向孔时的现场工作数据进行了分析和数据拟合,得出了天井钻机在最佳工作状态时的工作轴压、工作扭矩、钻进速度与牙轮钻头所在的掘进深度及普氏岩石硬度系数的数学模型,为设计先进的智能型大型深天井钻机全自动化导向孔钻进系统提供了理论依据。     

广西典型金属矿床氡气异常模式研究

通过对广西栗木锡矿、珊瑚钨锡矿、大厂锡矿、九毛锡矿、佛子冲铅锌矿和广西巴马县所略金矿等6个典型矿床氡气异常模式的研究,发现受断裂控制的矿床氡气异常模式：一类为正顶单峰或者双峰,另外一类大厂层状、似层矿矿床则表现出石油氡气异常模式即中间低且呈波状多峰,周边高,呈两高峰多组夹波状低峰的“波状峰”。若矿区地表条件适合氡气测量,该异常模式的建立能为更多需要开展氡气测量的矿区提供借鉴。