共查询到19条相似文献,搜索用时 500 毫秒
1.
2.
复曲面镜片铣磨后,一个剖面的曲线为真圆,而另一个与之垂直的剖面内曲线为一复杂曲线,通过分析成形运动,导出了复杂曲线的方程,将理想圆与该曲线进行比较,得到了复曲面镜片面形误差的计算公式,并利用计算机计算出了面形误差,从而得出了当镜片回转半径等于176.66mm,砂轮直径越大,砂轮所扳角度避免在30°左右取值,能减小复曲面镜片面形误差,提高面形精度的结论.为合理选择机床参数提供了理论依据. 相似文献
3.
4.
复杂曲面自动化测量程序生成及分析 总被引:4,自引:0,他引:4
着重分析了基于坐标测量机的复杂曲面自动化测量中的测量程序生成和曲面轮廓度评价方法问题。对一张曲面,采用单一测量头,根据曲面的最小曲率半径确定测量头半径,根据曲面精度等级、机床加工能力、曲面的复杂程度等因素确定采样样本大小。利用自适应采样方法,使得采样点的分布完全符合曲率大处采样点多、曲率小处采样点少。评价曲面轮廓度时,针对无基准要求的面轮廓误差采取曲面的最佳匹配,给出了一个参数曲面的最佳匹配算法。 相似文献
5.
6.
7.
机床的各种误差是影响机床加工精度的重要因素,其中机床几何误差是主要的误差来源之一。为消除机床几何误差对加工精度的影响,以球头刀三坐标数控(numerical control,NC)铣削加工为研究背景,基于齐次坐标变换理论与刚体运动学方法,结合机床运动链拓扑结构分析,将机床几何误差映射到球头刀刀心的位置误差上。根据球头刀铣削工件表面成形原理,考虑机床几何误差与球头刀刀心位置间的映射关系,构建出刀心曲面与工件表面/设计曲面之间的正逆向计算模型。通过该模型求解出消除机床几何误差的编程刀心曲面,将该曲面导入CAM软件,即可获得消除机床几何误差的NC加工程序。通过曲面实例进行计算和仿真,佐证了该方法的可行性。 相似文献
8.
针对一种新型并联机床的实际加工要求,提出了灵活度指标。该灵活度指标选取为刀尖点服务区的面积与服务半球面积的比值,提出了基于曲面分析的灵活度计算方法,并分析了结构参数,运动学参数对机床主进给机构灵活度的影响,分析计算结果表明,该新型并联机床的主进给机的灵巧性好,可以实现大倾角加工。 相似文献
9.
10.
11.
采用以铣代车,使卡罗塞尔箱体外圆的尺寸在数控镗床上不难控制,成败的关键是外圆表面母线的直线度.当工件、刀具的轴心线垂直相交,且各自围绕自己的轴心线回转时,加工出的工件表面是球面的一部份——球台.介绍了该两轴线所形成曲面的任意点曲率半径的试计算公式与加工工艺,用以解决其球面误差和各点的曲率半径不相等的问题,以解决外圆表面母线的直线度的问题. 相似文献
12.
J.D. Garratt 《Precision Engineering》1982,4(3):145-151
An instrument has been developed which can measure not only radius of curvature but also form deviation and surface texture at the same time. A computer is used to mathematically separate the form from the texture. The technique can be applied to the measurement of cross track curvature of bearing raceways and to other precision components whose form is defined as a circular arc, or a straight line, in which case angle will be measured instead of radius. The measurement of other forms such as parabolic, elliptical, hyperbolic and aspheric are the subject of continuing development. The instrument provides a distinctive and useful advance in measurement by the stylus method, offering possible solutions to many obdurate problems in the field of surface metrology 相似文献
13.
Two methods for microscopically measuring the curvature of strongly curved surfaces are compared: one using a Michelson interferometer-type microscope and one using a novel reflectometrical method implemented in an epi-illumination microscope. The curvature values obtained with the two methods were very similar, but the latter proved to be by far the simplest. Curvature measurements on the front surface of the facet lenses of various dipteran flies revealed that facet lens diameter and radius of curvature are linearly related over a wide range of facet lens sizes. 相似文献
14.
采用刀尖圆弧半径为0.4 mm的刀片,以0、0.4 mm、0.8 mm、1.2 mm为刀尖圆弧半径补偿值,得到球面曲率半径不同的四个试件,基于三丰C-3200测量仪对球面轮廓度进行测量,分析刀尖圆弧半径补偿对球面零件车削加工的影响。分析结果表明,在进行凸球面零件加工时,HNC-818A数控系统中的刀尖圆弧半径补偿功能有效,球面的曲率半径与刀尖圆弧半径补偿值的单调性一致。当刀尖圆弧半径补偿值线性变化时,球面的曲率半径呈非线性变化。当设定刀尖圆弧半径为真实值时,球面轮廓最为理想。在球面零件加工实践中,使用刀尖圆弧半径补偿功能,精加工采用可转位机夹车刀,通过试切法合理修改刀尖圆弧半径补偿值,可以提高球面零件的车削加工质量。 相似文献
15.
G. A. Lenkova 《Optoelectronics, Instrumentation and Data Processing》2017,53(5):431-441
This paper considers shape features of the surface structures of multifocal intraocular lenses (IOLs), which, unlike bifocal IOLs, generate additional foci or extends the depth of focus, which not only corrects near and far vision but also provides good vision at intermediate distances. Expansion of the field of clear vision is achieved due to the effects of diffraction, interference, and refraction (change in the radius of curvature of the lens surface). The optical characteristics of the most famous multifocal IOLs (trifocal and quadrafocal lenses and lenses with extended focal area) are given. 相似文献
16.
Jianfeng Song Yingxue Yao Yonggang Dong Bo Dong 《The International Journal of Advanced Manufacturing Technology》2018,95(1-4):11-25
When machining a free-form surface automatically and digitally, especially in the case of sophisticated surface shapes, it is very difficult to control the surface quality, and thus sophisticated surfaces are usually polished using manual labor. Over the past few years, there has been little attention to the calculation of material removal depth models and construction of theoretical roughness models considering the influence of the curvature radius. Bonnet polishing can be automatically adapted to polish complex free-form surfaces. This paper explores key problems related to forecasting surface quality with respect to bonnet polishing of free-form surfaces. First, for the convex and planar sub-regions, this paper deduces the relationship expressing the maximum pressure distribution and the curvature radius, and presents a computational expression for material removal depth, taking into consideration the influence of the curvature radius. An expression is also deduced for the dwell time relationship between the adjacent processing points according to the experimental results pertaining to the material removal depth. From this, a theoretical roughness model is constructed that relates the bonnet curvature radius and the workpiece curvature radius. The validity of the experiments is summarized in the conclusion. The research findings provide a basic theory for the prediction of surface quality that can be automatically adapted to a free-form surface shape in bonnet polishing. 相似文献
17.
运用弹流润滑理论,针对工业链中套筒和销轴之间的接触,采用无限长线接触热弹流模型研究表面波纹度对不同型号链条接触区的油膜厚度、压力及温度的影响。结果表明:表面波纹度会引起油膜压力、膜厚和温升的显著波动;对于小的当量曲率半径,膜厚波动的振幅同表面波纹度的差距很大,接近100%,但是随着当量曲率半径的不断增大,膜厚波动的振幅逐渐降低,最后表面波纹度已不发生弹性变形;膜厚的波纹度振幅变化还与波纹度的波长有关,波长越长,波纹度振幅变化的速度越慢;在某些特定接触条件下,波纹度表面可以形成比光滑表面更厚的油膜。 相似文献
18.
反求工程中过渡曲面特征提取算法研究 总被引:18,自引:1,他引:18
针对反求工程中常见的过渡曲面特征,提出了一种过渡曲面特征的提取算法。该算法包括数据分块和过渡曲面参数提取两部分,在数据分块算法中,通过数据精简,曲率估算和曲率比较等步骤,将过渡区域的数据点从原努点云数据中分离出来,在过渡曲面参数提取算法中,通过圆柱拟合和过渡区域跟踪算法,计算出一系列过渡曲面的截面线,该算法和已有的过渡曲面特征提取算法相比,无需人工交互,而且适用于等半径过渡曲面特征和变半径过渡曲面特征。 相似文献
19.
宽范围大曲率半径数字化非接触测量系统 总被引:4,自引:0,他引:4
本文提出了一种新颖的利用激光偏振干涉体系产生非接触的牛顿环并与CCD图像处理技术相结合的测量方法。可测量的曲率半径为1~25m,具有很宽的测量范围;非接触测量不会损坏高精度表面;并可测试任意反向率的凹、凸球面,而测试体系结构却非常紧凑。干涉条纹经计算机数据处理可自动、快速获得测量结果。经误差分析,测量的相对误差△R/R优于0.3%。 相似文献