共查询到20条相似文献,搜索用时 187 毫秒
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结合轴承沟道形状误差的几何特性,提出了轴承沟道形状误差的最小二乘评定,详细阐述了利用最小二乘算法求解轴承沟道形状误差的过程和步骤。该算法采用最小二乘法拟合每条线轮廓的中心,得到一个空间圆及方程;求解空间圆与每条线轮廓所在平面的交点坐标;计算每条线轮廓上测点至所对应的每个交点的距离中最大值和最小值之差,从中找到最大极差值,即得到包容整个轴承沟道的最小二乘形状误差值。该算法简单明确,具有精度高、易于计算机程序实现、易于推广应用等特点。 相似文献
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基于神经网络边缘提取的工业断层成像图像拟合 总被引:1,自引:0,他引:1
通过工业计算机断层成像图像边缘拟合,可获得矢量化的曲线,进而获得工件的计算机辅助设计图纸,实现基于工业断层成像的机械零部件逆向设计。在用两组细胞神经网络对图像进行分割的基础上,进行边缘跟踪和曲线的多维拟合。通过横截圆和轴线的拟合,实现对圆柱形目标的拟合。轴线拟合时,将各层圆心坐标分别投影到xz平面和yz平面进行最小二乘拟合,以降低计算复杂度。对发动机切片图像进行实验,根据拟合得到的参数得出了圆柱形目标的计算机辅助设计图,其拟合均方误差小于0.3像素2。对不规则目标,讨论了基于最小二乘法的分段三次曲线拟合方法在边缘曲线拟合中的应用;对发动机切片图像目标区域进行实验的拟合均方误差均小于0.6像素2。实验结果和误差分析证明,文中的拟合方法是有效的,实现了基于工业断层成像的逆向设计所必需的位图矢量化。 相似文献
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同轴度误差快速评定新算法 总被引:1,自引:0,他引:1
针对空间最小二乘拟合同轴度基准轴线算法效率较低的问题,提出一种同轴度误差快速评定新算法。根据空间最小二乘法拟合直线的思想,利用两次投影法,先将n个基准要素的轮廓圆心正截面投影到xo Y面上,求取拟合的基准轴线与xo Y面的交点,再将n个被测实际要素轮廓正截面圆心投影到xo Y面上,将三维问题转化为二维问题,进行同轴度误差评定。并对一组数据进行了MATLAB仿真,结果证明该算法准确,便捷且计算速度大幅度提高。 相似文献
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针对曲轴轴颈同轴度的快速检测的需求,文章提出了一种基于三维点云的同轴度误差视觉测量的方法。文章应用激光扫描仪获取待测件的三维点云模型,计算获取等间距的轴颈点云切片;然后,提出Pratt-RLTS法来得到各个点云切片的圆心,进而根据各切片圆心以最小二乘法获取公共基准轴线,最终实现同轴度误差的测量。实验结果表明:文章圆拟合方法对比最小二乘圆法、最小包容圆法、RANSAC等方法更准确稳定,与三坐标测量机结果相比最大绝对误差均值不过超过4.8μm,可以满足快速高效测量曲轴同轴度误差的实际需要。 相似文献
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轧机压下螺纹副承载特性测试研究 总被引:9,自引:1,他引:9
依据相似准则,制作3500mm中厚板轧机电动压下传动螺纹副1/3的测试模型,采用电测法获取悬臂螺牙弯曲应变值,模拟实际轧制力和过平衡力作用下螺纹副螺牙各层载荷大小及分布。螺纹副测试结果和边界元、有限元法数值计算结果相比,螺牙层载荷大小和分布规律基本吻合,证明电测法可行、直观且可靠。通过测定数据,证实了轻重两种载荷工况的不同承载特性,还发现螺母与丝杆轴线错移或倾斜的微尺度行为对载荷大小及分布影响极大的重要现象,为提高压下传动螺纹副寿命及可靠性提供了重要思路。 相似文献
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This note describes a method for measuring probe alignment errors on precision cylindrical coordinate measuring machines. Specifically, this method is used to determine the minimum distance between the line of travel of the center of a spherical probe tip and the axis of rotation of a rotary axis. Within the Timken facility, we refer to this error as intersection error [Bryan JB. Private communication; 7 June 1992]. In addition to intersection error, this method determines the position along the probe line of travel at which the center of the probe tip passes nearest to the axis of rotation. This position is commonly referred to as probe offset error. It is used to adjust the probe location such that its radial position is zero where it intersects (or nearly intersects) the axis of rotation. In this way, the probe tip location is datumed to the axis of rotation. 相似文献
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J.J. Stobo 《Wear》1980,65(1):131-133
A numerical solution is developed for the equations governing the laminar hydrodynamic flow in a sector-shaped thrust bearing with its axis parallel to but offset from the rotational axis. The lubricant viscosity is assumed to be a function of the temperature distribution in the fluid film. The rotating plate is assumed to be an isothermal component and the heat conduction equation in the stationary component is solved simultaneously with the governing equations of the fluid film. Thermal effects are shown to be pronounced especially at large values of offset from the rotational axis. 相似文献
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现有磨削加工技术已经无法满足发动机的需求,故提出航空发动机叶片数控智能磨削加工技术。应用参数线法规划叶片磨削加工轨迹,以此为基础,提取磨削加工余量,模拟与计算对应数值,适当处理获取的叶片磨削加工轨迹与加工余量数据,推出叶片数控智能磨削算法(数控车床转轴、直线轴与压力轴运动控制模型),以此控制数控车床运动姿态,并通过刀位点偏移补偿叶片的反变形误差,实现了航发叶片的数控智能磨削。实验数据表明:应用该技术后叶片型面加工前后粗糙度变化明显;叶片边缘加工误差保持在标准误差范围内;叶片根部粗糙度得到了大幅降低,充分证实了该技术具有可行性。 相似文献
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为进一步提高模切纸张精度,在模切机叼纸机构前加装一套纸张定位装置.该装置基于机器视觉原理,在模切机的前规、侧规处安装3部微型相机,运用图像处理的方法粗略定出纸张边缘点位置,然后采用一维灰度矩法对边缘点进行亚像素级边缘检测,再通过最小二乘法直线拟合出纸张边缘所在直线的方程,计算出3幅图像中各纸张偏离零位位置的距离值.根据3个偏移值指导叼纸机构进行适当微调,可使模切精度达到0.02mm. 相似文献
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J.-J.J. Wang C.-Y. Huang 《The International Journal of Advanced Manufacturing Technology》2004,24(11-12):910-918
Cutter runout due to cutter axis offset is quite common in a milling process, yet it is difficult to directly measure the runout geometry of a ball end cutter during the cutting process. This paper presents an analytical method for the estimation of cutter radial offset via forces in ball end milling. Closed form expression for the total milling force in the presence of cutter offset is first obtained. Fourier series coefficients for the offset related force component are shown to be expressed explicitly in terms of the offset geometry and serve as the basis for the identification of the offset geometry from the measured cutting forces. The offset geometry including its magnitude and the phase angle are directly calculated from the measured force component at the spindle frequency through two algebraic expressions. The identification method is finally validated by milling experiments. 相似文献