钢管外圆砂轮(砂带)磨削装置的原理及应用

阐述钢管外圆砂轮(砂带)磨削装置的原理及应用,结合我国目前钢管外圆磨削工艺的现状,提出了一种由五组磨头组成的外圆砂轮(砂带)磨削方法,这种磨削方法在钢管外圆表面磨削加工的批量生产中,被证明能使钢管外圆磨削效率与磨削质量大大提高。     

磨削直线轴承弧形外圆的新方法

在分析外圆工件贯穿无心磨削原理的基础上 ,提出一种既可保证磨削圆度又可提高磨削效率的直线轴承弧形外圆磨削新方法 ,并设计了辅助夹紧装置。     

磨削直线轴承弧形外Iil的新方法

在分析外圆工件贯穿无心磨削原理的基础上,提出一种既可保证磨削圆度又可提高磨削效率的直线轴承弧形外圆磨削新方法,并设计了辅助夹紧装置.     

轴颈外圆磨削成圆过程的双转子耦合模型及仿真算法

主轴轴颈外圆的圆度对机床主轴部件的回转精度具有直接而重要的影响。磨削加工是实现轴颈外圆高精度加工的最重要的手段。虽然磨削技术在主轴外圆加工上已长期应用,但是利用现有的研究成果,还难以对一个既定的磨削系统的磨削成圆过渡过程进行完整有效的定量仿真,也难以对磨削工件的最终圆度进行科学合理的预测。在吸收国内外磨削转子系统模型成果的基础上,进一步考虑外圆磨削过程中砂轮和工件之间的相互耦合作用、材料去除、转子振动及变形协调规律,建立了外圆磨削系统的双转子耦合振动模型,提出了模拟轴颈材料去除和圆度变化的"磨削力-瞬时磨削深度"迭代算法。利用所建立的双转子模型和迭代算法,对不同磨削策略下轴颈外圆成圆的过渡过程进行了定量仿真,再现了轴颈材料去除和外圆轮廓变化的全过程;比较研究了不同磨削策略对磨削效率和最终加工圆度的影响规律。进行了相应的磨削试验和对比验证,试验结果证实了所提出的轴颈外圆磨削的双转子模型和迭代算法的有效性和合理性。     

金属切削机床的调整与保养——第6讲 无心外圆磨床的调整

无心外圆磨削是机械加工中一种高效率、高质量的磨削方法。早在轴承、汽车、拖拉机、机床工具、油泵油嘴、纺织机械、航空、电机和仪表制造业中得到了广泛的应用,现在又发展到用无心磨削精加工发动机中的凸轮轴、曲轴和电机主轴等大中型零件。它比多砂轮外圆磨削具有更高的质量(如圆度和同轴度)和效率,例如精磨6个轴颈的球墨铸铁凸轮轴,从铸件一次磨到成品,磨削余量为3～3.5mm,表面粗糙度达R_α0.4μm,单件时间为35s。在机械制造业中,凡具有批量生产的中、小型圆柱形的轴、孔或回转型的成形表面等零件,若采用外圆无心磨削,则产品质量会更高更可靠,效率也更高,较为经济合理。但上述效果的获得,无心磨床的调整技术非常关键。     

外圆磨削颤振通用模型及稳定性研究

为有效解决外圆磨削微颤振问题,提高外圆磨削产品加工质量,基于再生颤振理论建立了一种外圆磨削动力学通用模型,该通用模型引入与砂轮宽度相关的重叠因子,充分考虑工件与砂轮的再生颤振关系,可通用于外圆纵向磨削和外圆切入式磨削;运用牛顿迭代法对带有时滞的超越方程进行数值求解,并结合高斯消元法提升迭代收敛速度,利用延拓算法连续提供有效初始值,提高迭代结果的准确性,可获得准确的磨削稳定性边界。以复杂切入式磨削进行磨削颤振数值模拟计算和实验研究,实验结果表明该通用模型可有效应用于外圆切入磨削颤振过程,通过该模型选择的磨削加工参数可有效避免磨削微振纹现象,可有效提高外圆磨削加工质量和加工效率。     

高精度切入式外圆磨床模块化设计

一、问题的提出随着机械工业的发展,磨削加工方法也从手动、半自动型向提高自动化程度、提高加工效率和提高加工精度方向发展。国外从七十年代开始在磨削加工上的一个重要发展,就是广泛采用高速、高效切入磨削,用以作为一种大批量生产用高精度外圆的磨削加工。当前国内外的磨削加工中,切入式磨削大量广泛地应用。它对提高加工效率、对成型加工、对实现自动化连续控制、对自动测量以及各种自动化技术的应用都提供了极其有利的因素。为此,国外较多的外圆磨床制造厂均在万能外圆磨床基础上大量地重点派生发展切入式外圆磨床。在此基础上,进一步采用数控技术     

日本精工精机(Seiko-Seiki)公司的内圆磨床适应控制

一、内圆磨削加工的一般情况内圆磨削加工和外圆磨削加工相比较,情况较为特殊,首先是砂轮直径受到磨削孔径的限制,砂轮线速度比外圆磨削低,砂轮磨损较快,而且易于产生不均匀磨损。其次,砂轮直径小,而且容易磨损,在磨削过程中磨孔直径与砂轮直径之比(即K_R值)变化范围比外圆磨削大,容易影响磨削质量。而在内圆磨削中砂轮轴的刚性又是个薄弱环节,磨削时对零件形状误差的修正能力较差,不易获得高的磨削精度。在一般的恒速进给磨削条件下,磨削起始时在磨削抗力的作用下,砂轮产生弯曲变形,此时尚未进行磨削,随着进给量的增加磨削力的增大砂轮轴弯曲     

基于单颗磨粒的高速外圆磨削成屑机理研究

高速磨削是解决磨削效率和磨削质量完美统一的一种可能途径,但对于高速外圆磨削机理的研究并不多见。基于切削仿真软件,构造了单颗磨粒高速外圆磨削仿真模型,对高速外圆磨削机理进行了仿真试验研究,研究结果表明:钛合金在单颗磨粒高速磨削作用下经历了滑擦→耕犁→成屑→滑擦4种状态变化;工件在磨屑形成之前,力与温度均呈上升趋势,随着工件温度的升高,磨削力出现拐点并急剧下降,成屑过程中磨削温度达到最高值时,磨削力降至最小值。     

基于磨削力模型的外圆切入磨削声发射信号研究

磨削过程中磨削力与声发射信号均方根值有较强的对应关系,对工件表面加工质量有很大影响。为便于研究外圆切入磨削质量和效率,在基于外圆切入磨削力的数学模型研究基础上,建立了声发射信号AERMS与径向进给速度、砂轮线速度及工件线速度的关系模型。通过磨削实验研究结果,验证了上述方法的有效性和实用性。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

Fifth International Summer School on Screw-Theory Based Methods in Robotics

正3-11 September,2014University of Bologna,Bologna,Italy www.summerscrews.org summerscrews2014.ing.unibo.it SUMMER 20SCREWS 14In 2014,our screw-theory school comes to the world's oldest university.In early September,Summer Screws'14 will gather six experts in the application of screw theory in robotics and up to 40 participants at the University of Bologna,Bologna,Italy.The school will teach attendees how to apply existing methods and empower them to develop new ones in their own research.The basic theoretical notions will be introduced in a rigorous manner,emphasizing examples,applications,and exercises.Scholarships are available.     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

INDUSTRIAL ENGINEERING AND VISUALISATION-A PRODUCT DEVELOPMENT PERSPECTIVE

Taking the actual project of teaching and researching process for example, the relationship between the industrial engineering and product development is discussed. And use the novel visualization technology to support the industrial engineering and product development. How to use the new computer modeling and simulating technologies to support the product development and industrial engineering, is introduced especially. The support includes both domestic products and industrial systems. The visualization and computer technologies take a very important role in some system or multi-direction modeling, those technologies mentioned above can help the industrial engineers study the effect of design on the whole life circle, including the producing steps. So the engineers can avoid making the wrong decision which may cause bad effects on the whole industrial engineering.