基于热致线膨胀与行程放大的温度势能自锁夹紧装置

在环境污染日益严峻的形势下,绿色可持续发展成为一项重要的议题。夹具是制造业中应用广泛的一种装置,设计一种能源利用率高、无污染的夹紧装置对于实现节能降耗有着重要意义。设计一种自锁夹紧装置,利用温度敏感材料产生线性热膨胀效应作为微位移驱动装置,结合行程放大机构将微量的位移放大为显著的位移,并利用驱动装置本身的温度势能保持自锁夹紧。此夹紧装置具有能源利用率高、无污染、自锁性能优良、稳定性好的优点。     

Rock failure with weak planes by self-locking concept

In order to investigate failure of a rock mass having planes of weaknesses, a three-dimensional model is proposed based on the self-locking concept in friction analysis. In the case of two-dimensional problems, the model gives the same results as that of the Mohr–Coulomb criterion. The three-dimensional model can be reduced to the two-dimensional model, if the weak plane is parallel to the intermediate principal stress and/or the intermediate stress is equal to the minimum principal stress. The results indicate that the influences of three principal stresses and mechanical parameters of the weak plane on spatial failure region are remarkable, in terms of shape and range, that the spatial failure region becomes smaller as the mechanical parameters increases, and the weak plane will never fail when some threshold of mechanical parameters is reached, no matter what values of weak plane strike and dip will be. The spatial failure region becomes smaller with increased values of the intermediate and minimum principal stresses, conversely it becomes larger with the maximum principal stress increased. Additionally, the influence of bottom hole pressure on the failure range of weak plane is analyzed, for bore holes in naturally fractured formations, with the help of a local coordinate system.     

工件快速自动夹紧机构的设计

介绍了一种工件电动快速自动夹紧机构,并对该机构工作原理及特点进行了分析和论述。     

静态推靠式旋转导向钻井系统的钻压传递效率

国内研制的静态推靠式旋转导向钻井系统正全面开展现场试验及初步应用,该系统正常钻进时导向翼肋施加到井壁上的静态推靠力会产生较大的摩擦力,有可能影响钻压传递效率和钻井速度。为此,基于该系统的结构及工作原理,考虑井壁无台阶和有台阶两种情况,分别建立了钻压传递效率分析模型,模拟分析了钻压传递效率随名义钻压、井壁摩擦系数,以及导向翼肋推靠力和前倒角的变化规律。研究结果表明:(1)该旋转导向系统对名义钻压有最小值要求,适当提高名义钻压有助于提高钻压传递效率;(2)无论井壁是否有台阶,如果导向翼肋推靠力之和越大、井壁摩擦系数越大,那么钻压传递效率就越低,当井壁有台阶时钻压传递效率明显低于井壁无台阶时的对应值;(3)井壁有台阶时导向翼肋前倒角对钻压传递效率影响明显,前倒角越大则钻压传递效率越低(甚至自锁)。结论认为,该研究成果有助于指导钻井现场合理选择和调控钻压。     

渐开线凸轮夹紧机构的设计

研制出一种新的夹紧机构--渐开线凸轮夹紧机构.并给出了其设计步骤和计算公式.它相对于圆偏心夹紧机构具有更大的夹紧力和夹紧行程,具有更好的自锁性能.     

链环式超越离合器自锁特性分析及全区间自锁的实现

链环式超越离合器在使用过程中 ,常常由于磨损和安装位置问题而不自锁 ,本文通过对链环式超越离合器自锁模型的分析 ,改善了链环式超越离合器的自锁特性 ,使链环式超越离合器在设计范围内实现了全区间自锁 ,并通过试验证明了这一点。     

蜗轮副在自锁条件下的传动特性分析

用能量法推导出了蜗轮副的自锁条件，并给出了自锁蜗轮副在蜗轮受驱动力的情况下，驱动蜗轮副所需要转矩的计算公式。     

周转轮系的内力矩、功率流与自锁

应用离散方法 ,深入分析了两种 2K H型行星轮系的内力矩和功率流 ,发现 2K H型行星轮系属于封闭差动轮系 ;其中 ,正号机构存在循环功率流。循环功率流不仅降低了正号机构的效率 ,而且在某种情况下还会使轮系自锁。同时 ,分析了 3K型行星轮系的内力矩、功率流和自锁问题。     

空间微型合作目标捕获装置的研究

针对空间微型合作目标跟踪捕获任务,研制了具有稳定抓握、多感知、高刚度、高精度、大夹持力、大容错误差校正能力的新型捕获装置.其中,三指形手爪是带有手眼视觉的多传感型手爪,驱动链里加入一套高效率质量轻的反转自锁机构,同时手爪与微型目标器配合设计,冗余容错技术的引入及紧急解锁机构的设计保证了手爪的高可靠性.手爪的试验与测试,证明了手爪优越的抓捕性能与可靠性.     

Self-locking analysis in closed kinematic chains

Self-locking analysis in closed kinematic chains is sometimes likened to kinematic singularity analysis, especially when mechanisms are characterized by more than one degree of freedom. Although in singular configurations a mechanism is obviously locked-up since joint constraint reactions and friction forces rise to infinity, this approach identifies only a condition sufficient for self-locking, while the phenomenon actually occurs in a larger domain, the size of which depends on the values of friction coefficients.The paper proposes a definition of self-locking for multi degrees of freedom mechanisms and presents an algorithm for computing the geometrical locus that corresponds to a specific self-locking configuration. This methodology is then demonstrated on a simple parallel kinematic mechanism with two degrees of freedom.