S形刃球头立铣刀的数学模型

建立了S形刃球头立铣刀内前刀面、外前刀面及螺旋后刀面、平面后刀面的数学模型。该模型的建立为球头立铣刀刃磨参数选择及刃磨装置设计具有重要的作用。     

一种新型球头立铣刀前刀面成型方法的研究

在分析现有球头立铣刀刃磨方法的基础上,提出了一种新的球头立铣刀前刀面刃磨方法。本文建立了该方法的数学模型,给出了前刀面方程,对球刃主切削刃的法前角分布、主切削刃的刃形进行了研究。     

整体硬质合金球头铣刀螺旋槽建模技术研究

球头铣刀外形复杂,工序繁多,在曲面加工中应用广泛。对整体硬质合金球头铣刀刃线和螺旋槽进行数学建模,采用等导程刃线模型生成S型球头刃线,解决球面刃线与柱面刃线过渡不光滑问题。采用蝶形砂轮刃磨螺旋槽,求解砂轮刃磨位姿。利用MATLAB对球头铣刀刃线模型进行仿真验证,计算砂轮位姿变换过程,并基于MATLAB软件中GUI模块设计砂轮磨削工艺系统。     

基于SolidWorks的立铣刀三维实体建模

基于锥形砂轮加工立铣刀螺旋槽的过程,介绍了在SolidWorks环境下,以砂轮形状、砂轮相对铣刀毛坯的安装位置、砂轮与铣刀毛坯端面的初始位置以及砂轮运动轨迹为条件,采用实体扫描切除功能模拟螺旋槽刃磨过程进行三维实体建模的方法;将建模过程参数化,分析了螺旋槽刃磨砂轮安装位置对螺旋槽槽型的影响,在此基础上提出了满足槽型设计参数的砂轮安装位置反向求解方法;基于立铣刀侧刃与端刃刃磨过程,依次建立立铣刀侧刃后刀面、端刃齿隙与端刃后刀面特征,获得与刃磨工艺相匹配的立铣刀三维实体模型。实例验证结果表明,该方法建立的三维实体模型符合设计参数要求,并且表面光滑可直接用于CAE仿真计算。     

球头立铣刀的建模设计及仿真系统的研究

以球头立铣刀的正交螺旋形刀刃曲线为基础。设计了锥形砂轮刃磨铣刀前后刀面的方式。分别推导与建立了具有等法向前角的前刀面、等主后角的后刀面的球头立铣刀的数学模型。并根据模型开发了球头立铣刀的计算机仿真设计与分析软件。     

车刀智能化刃磨的理论研究与仿真分析

针对现有车刀刃磨方法的局限性,建立车刀各刀面刃磨数学模型,设计出刃磨装置,并进行仿真分析,通过车刀位姿调整,实现任意一个被刃磨刀面与砂轮的磨削平面重合,以获得最佳刃磨成形表面质量,最终为开发机床刀具刃磨中心奠定理论基础.     

等法向前角和等径向后角微细球头铣刀刃磨研究

微细球头铣刀因其在制造复杂的曲面和零部件方面具有很大的优势而广泛应用于微机械加工领域。目前多轴数控磨削方法仍是实现微细球头铣刀批量化制造的主要方法,但是由于微细球头铣刀尺寸小,误差敏感性大,在刃磨过程中难以保证其制造精度和质量,因此迫切需要精确高效的刃磨方法来提高微细球头铣刀制造精度,降低其刃磨制备难度。为此,基于球面等导程螺旋线切削刃曲线,提出了用于等法向前角前刀面的刃磨模型。为了实现球部和圆柱形部分的后刀面的平滑连接,提出了等径向后角后刀面的刃磨模型。基于提出的刃磨模型和6轴CNC磨床运动原理,通过Matlab编程求解等法向前角和等径向后刀面微细球头铣刀刃磨过程中机床各轴运动轨迹。最后,通过磨削仿真和实验成功制造了直径为0.5mm的硬质合金微细球头铣刀,其最大几何误差不超过5%,从而验证了磨削方法的正确性和有效性。     

球头立铣刀端刃前刀面的刃磨仿真

以Solidworks为开发平台,对球头立铣刀端刃前刀面的刃磨过程进行仿真.建立了一套铣刀端刃前刀面的虚拟加工系统,通过刃磨参数优化,可实现端刃前刀面与周刃前刀面的光滑连接和良好的"S"刃形.模拟仿真发现端刃前刀面有一个很窄的刃带,分析了砂轮姿态对刃带宽度的影响.     

平行砂轮磨削圆弧头立铣刀后刀面的轨迹算法

针对圆弧头立铣刀周刃偏心型后刀面的磨削工艺、周刃与端刃后刀面磨削姿态变化剧烈导致磨削质量不高等问题,研究了一种采用平行砂轮磨削的圆弧头立铣刀后刀面轨迹算法。首先建立参数化设计的圆弧头刀刃曲线模型,并根据其模型定义了一系列活动坐标系及其转换关系。然后在其对应的坐标系下定义砂轮磨削姿态模型和相关参数,且通过其转换关系得到在工件坐标系下统一表达。最后进行仿真和实际加工来验证计算结果,并用检测仪对后刀面相关参数进行精度测量,验证了该算法的正确性和有效性。     

基于成型工艺的整体立铣刀三维实体建模

整体立铣刀因其良好的切削性能在航空航天、轨道交通和医疗器械等行业得到广泛应用。精确的三维实体模型是整体立铣刀数字化设计的基础,简化模型无法满足高性能立铣刀的精确建模需求。本文提出基于成型工艺的整体立铣刀三维实体建模方法,根据整体立铣刀实际制造工艺流程,以砂轮形状、砂轮相对刀具毛坯棒料的位姿关系以及砂轮运动轨迹为输入条件,采用NX12.0扫掠体功能依次建立整体立铣刀容屑槽、周刃后刀面、Gash面和底刃后刀面等结构,获得与成型工艺相匹配的立铣刀三维实体模型。刀具实例验证结果表明,该方法可有效提高建模精度和效率。     

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。     

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.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

RLS and LMS blind adaptive multi-user detection method and comparison in acoustic communication

RLS and LMS blind adaptive multi-user detection algorithm and multi-user detector was proposed to solve the problem of multi-user signal detection problem encountered in underwater acoustic communication networks.In simulation analysis,RLS and the LMS blind adaptive multi-user detector were designed and tested for synchronous and asynchronous multi-user communication process.The results of SIR comparison and MMSE comparison show that,both of the two methods can realize blind adaptive detection when any user change in multi-user communication,during this process,the training communication sequences are not needed.The RLS algorithm has about 5 dB higher in SIR compared with LMS algorithm,and the convergence velocity of RLS algorithm is also higher than LMS algorithm when the communication users change.RLS algorithm has better ability in multi-user detection than that of LMS algorithm,and it has great attraction and guiding significance for solving the problem of multiple access interference(MAI) in multi-user communication.