圆柱族包络面的非等径重构问题的理论研究

在机械设计与制造中 ,常遇到由一圆柱面运动生成的包络面是否能由另一半径不同的圆柱面运动来重新生成的问题 ,即圆柱族包络面的非等径重构问题。本文以等距曲面和包络理论为工具对此问题进行了研究。在得出包络面、轴迹曲面、等效轴迹曲面互为等距曲面的结论的基础上 ,研究了轴迹曲面可展与不可展两种情况下的非等径 (一次 )包络重构问题 ,得到了一些有价值的结论。然后研究并提出了两重包络重构方法。这些结论和方法对指导圆柱族包络面的设计与制造具有重要价值     

Discussion on the problems related to NC machining of toroid-shaped taper cutter with constant angle between cutting edge and the cutter axis

Defining the helical angle as the angle between the cutting edge and revolving axis of the cutter presents the designing models of the cutting edge and helical groove of a toroid shaped taper cutter. Under the condition of a certain revolving speed, the relative radial and axial feeding speeds of the grinding wheel in two-axis NC machining of the cutter are deduced. The models for calculating the actual obtained groove and the simulation-method of computer are also provided.The surface near to the top of the end cutter has no helical cutting edges and infinite feeding speeds of NC machine. It is necessary to adopt a supplementary cutting edge. A supplementary cutting edge is designed as a cutting edge with a constant pitch. This paper provides valuable reference for the design and NC machining of this kind of toroid shaped taper cutter.     

基于熵函数与离差最大化的客观赋权法研究

针对大型机械设备安全评价中评价指标客观权重随加权方法的选择而变化的问题,提出一种基于熵和评价对象离差最大化的客观综合赋权模型。该模型将不同客观赋权法得到的权重向量视为指标真实客观权重向量的离散随机变量,将权重系数定义为权重系数的概率函数的随机变量,考虑不同客观加权方法得到的权向量的不确定性和实际目标权向量的一致性要求,基于熵函数获取权系数的约束方程;针对权重与对象评价值的关系,将评价对象离差的最大化作为上述权重系数约束函数的补充,构建客观综合赋权模型,使获取的指标客观权重仅与其携带的原始信息相关,极大的提高了大型机械设备安全评价的客观性。算例验证了该模型的合理性和有效性。     

Measurement of the contact area of a dovetail milling cutter using an ultrasonic method

Since there is no reliable mathematical model to analyze a multi-points contact simultaneously, the most effective way to know the contact area is to use experimental method directly. This study measures the contact area between a dovetail milling cutter and a steel plate by using ultrasound for regional scanning. This is a novel application for milling cutters and has not been applied before. The transducer emits an ultrasonic pulse to detect the contact surface. If contact occurs, the pulse is partially transmitted into the specimen. Therefore, the signal reflected back to the pulse receiver is reduced. The amount by which the signal amplitude is reduced is a measure of the degree of contact.     

一种快速得到挖掘机挖掘包络图的新方法

挖掘机工作装置作业由三个油缸复合动作及铲斗和土石方的相互作用实现。利用虚拟样机技术,对工作装置作业过程进行运动仿真与动态显示,使得设计人员在设计阶段就可以看到其设计方案的合理性、机构参数设计是否最优。基于这种实际情况,应用Matlab软件中的SimMechanics,介绍一种快速得到挖掘机挖掘包络图的方法。准确快速的分析工作装置的基本挖掘尺寸,如最大挖掘高度、最大挖掘深度、最大挖掘半径、最大水平挖掘半径。通过实例可以看出,该方法工作量小,简单快捷。     

基于力矩电动机的双摆动铣头设计

简要介绍力矩电动机的结构、基本参数及其选用,给出五轴联动高速雕铣机的总体方案设计以及双摆动高速铣头结构和其关键件的设计,并用Pro/E对设计进行实体建模.     

A study on the design of error-free spur slice cutter

A design method of error-free spur slice cutter is proposed according to urgent demand for the slice cutter in actual production. The structure of the rake face is determined according to technological realization of the design, manufacturing, and tool grinding. On that basis, the mathematical model of the rake face is built. Taking the error-free design as the goal, the mathematical model of major flank face is established based on the principle of the gear slicing. The mathematical models of designing angle and working angle are constructed by the equivalent methodology, spatial geometrical theory, and conjugation theory of space surface. The validity of the above study results is verified by using a calculation example. The design method lays a theory foundation for the study of cutter parameter optimization, tool life, and other aspects.     

变速比齿条齿廓设计计算新方法

针对变速比齿条齿廓传统的啮合原理计算方法和数值计算方法,提出了一种变速比齿条齿廓设计计算的新方法.该方法不需要推导啮合方程,只需要知道变速比传动规律和齿轮的参数,就可快速计算得到变速比齿条的三维精确模型.根据具体算例进行了变速比齿条齿廓的设计计算及齿条加工;分析表明该方法理论正确、简洁明了、实用性强.     

基于新构形法的硬齿面插齿刀研究

从运动学角度出发,根据微分几何的包络运动原理,运用空间曲面族求解包络面的运动学方法,在砂轮磨削硬齿面插齿刀前刀面的过程中,建立砂轮截面圆曲线族的磨削点,砂轮曲面族的磨削线,砂轮曲面族包络面方程。并在分析,比较的基础上,提出确定硬齿面插齿刀侧刃空间曲线形状的新方法,建立了插齿刀侧刃空间曲线方程,研究一种新构形硬齿面插齿刀,使其不仅具有较高的构形精度而且具有合理的切削角度。     

基于空间包络理论的双刀盘铣齿关键参数优化

针对直线廓形的单铣刀盘铣削斜齿轮时齿面法向偏差较大且分布不均匀的问题,提出一种双铣刀盘铣齿法来减少齿面法向偏差。根据空间包络原理,对双刀盘铣齿进行建模并通过解析算法求取双刀盘所包络的端面齿形和齿面法向偏差。在不过切的前提下,求取刀盘间距的调整范围,并结合刀轴中心距分析两者与齿面最大法向偏差的关系。根据所得规律,以双刀盘铣齿关键参数—刀盘间距、刀轴中心距与法向偏差的关系为约束条件,通过调整刀盘间距与刀轴中心距,使用离散变量网格直接寻优算法,以减少齿面最大法向偏差为优化目标,对双刀盘铣齿关键参数进行优化研究,从而实现对齿面法向偏差的优化。通过物理样机试验表明,该优化方法可有效减少齿面最大法向偏差。     

一种轴承沟道车削防偏位方法研究

在轴承套圈车削加工中,沟道偏位是轴承套圈车削加工的一个实际问题.套圈在夹具中定位不准是引起套圈沟道偏位的主要原因.设计一种装置,利用装置中连接有故障信号的触头和沟道偏位的套圈接触,通过触头连接的导线把故障信号反馈给电气控制系统,促使机床自动停止,从而达到防止沟道偏位的发生,提高了产品综合合格率,为产品从全检过渡到抽检奠定基础.     

利用代用滚刀加工插齿刀齿形的方法

根据被铣插齿刀的模数和压力角选择代用滚刀齿形,由齿厚变化量(歪变量)的大小来决定加工余量,解决了插齿刀加工费用高、周期长的问题。     

A hybrid stereo vision method using a correlation function and variable window based on voxel components

Existing stereo methods tend not to deal with depth discontinuity due to area-based problems, and so give inaccurate and noisy three-dimensional (3D) information in the surface morphology with steep disparity variations. In this paper, a hybrid stereo approach has been presented to estimate accurate, detailed and smooth information for the reconstruction and inspection of the surface morphology with both depth discontinuity and curved regions. It reduces the smoothing problems resulting from depth discontinuity by evaluating a new correlation function based on voxel components in the 3D disparity space. In addition, the connectivity of match candidate voxels is investigated to improve robustness to noise and then integer disparities are determined in the updated disparity space. A variable window based on voxel components is newly devised to cope effectively with curved regions as well as depth discontinuity. Sub-pixel disparities are accurately estimated through formulating the optimal error function in the variable window. We show how our results improve upon those of closely related techniques in terms of accuracy, robustness, matching density and computing speed.     

基于相移小波的信号包络提取方法研究

针对现有的包络解调方法对噪声宽容性差的不足，论文利用窄带调制类型信号相关函数的一个基本特性，建立了基于相移小波的信号包络提取方法。该方法采用Morlet小波为基小波，根据信号的中心频率和采样率等已知信息，能够有效地提取信号的包络，并且对低信噪比信号也具有良好的宽容性，仿真结果证明了该方法的有效性，并且证明了该方法的性能优于现有的其他解调方法。最后，采用该方法对一个实测的水声数据进行了分析处理，也取得了令人满意的结果。     

数控机床刀具磨损的振动监测法

在分析小波理论及BP神经网络的基础上,进行了刀具磨损试验研究。在时频域对刀具磨损状态的特征信号进行提取和分析,获得了反映刀具磨损状态的特征信号。将此刀具磨损特征量作为BP神经网络的输入样本对网络进行学习训练,完成对刀具磨损状态的有效识别。实验结果表明该方法是有效的。     

Generation of collision-free cutter location data in five-axis milling using the potential energy method

In five-axis milling, optimal cutter location data (CL-data) should be generated to have advantages over three-axis milling in terms of accuracy and efficiency. This paper presents an algorithm for generating collision-free CL-data for five-axis milling using the potential energy method. By virtually charging the cutter and part surfaces with static electricity, global collision as well as local interference is eliminated. Moreover, machining efficiency is simultaneously improved by minimising the curvature difference between the part surface and tool swept surface at a cutter contact point (CC-point).     

A study on the optimization method for a multi-body system using the response surface analysis

An optimization method, which minimizes the characteristic value of a system using response surface analysis, is presented. Plackett-Burman design is used as a screening method. Using the response surface analysis, second order recursive model function is estimated as an objective function. To verify the reliability of the model function, an F-test based on the analysis of variances table is used. Lastly, the sequential quadratic-programming method is used to find the value of design parameters. By applying the preceding procedure to a multi-body dynamic model, the optimization process presented in this study is verified. This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20–23, 2008. Sung Pil Jung received a B.S. degree in Mechanical Engineering from Ajou University in 2006. Currently he is a Ph.D candidate at Ajou University in Suwon, Korea. Mr. Jung’s research interests are in the area of multi-body & structural dynamics, optimization and computer aided engineering. Tae Won Park received a B.S. degree in Mechanical Engineering from Seoul University. He then went on to receive his M.S. and Ph.D. degrees from the University of Iowa. Dr. Park is currently a Professor at the School of Mechanical Engineering at Ajou University in Suwon, Korea.     

剃齿刀通用性校核方法研究

阐述利用计算机校核剃齿刀通用性的方法,具有快速、准确、方便等特点,同时还能为刀具刃磨提供基本参数,在 工程实践中具有重要的实用价值。     

基于NX运动分析的凸轮设计方法及其误差分析

提出了一种适合于凸轮正向和反求设计的基于NX运动分析的凸轮设计方法。通过对一凸轮实例的设计并比较了其与凸轮理论轮廓曲线之间的误差,得出了使用该方法设计的凸轮其误差完全可以被控制在机械加工所能达到的精度范围内。方法简单实用,为其他凸轮型线的设计提供了一种通用的参考方法。     

A study on a cooling method for bone grinding using diamond bur for minimally invasive surgeries

Miniature ball-end diamond wheels are widely used for bone grinding in endoscopic surgeries. During bone grinding, a considerable amount of heat is generated, which can cause thermal injuries to the tissues adjacent to bone, including nerves. In our previous studies, it was revealed that the strong adhesion of bone chips on the wheel surface promotes heat generation. To prevent adhesion, a surface-treated wheel was proposed, and it reduced the temperature elevation. However, we found that the proposed wheel cannot stably suppress the temperature elevation because the wheel effect depends on the coolant supply rate. In this study, a bone grinding method that stably suppresses temperature elevation was investigated. Based on the obtained findings, a cooling method using cold air was developed, and the temperature elevation was stably suppressed under a cold air supply.