【作者】 王成林；

【导师】 裘祖荣；

【作者基本信息】 天津大学 ， 仪器科学与技术， 2018， 博士

【摘要】 螺纹是空间复杂几何体,内、外螺纹在配合时,理论上是螺旋曲面的接触,而实际内、外螺纹都会存在加工误差,各自误差的表现形式及其在三维空间的分布情况不同,装配后难以对它们的实际配合作用效果进行量化分析。为简化起见,用虚拟理想螺纹与一个实际螺纹进行配合,这个虚拟螺纹可以反映实际螺纹在装配后的部分特性。螺纹标准ISO 5408:2009中定义,作用中径是一个虚拟理想螺纹的中径,该虚拟理想螺纹能够恰好包容实际螺纹并且在牙顶与牙底不发生干涉。本文从作用中径的定义出发,提出螺纹作用边界、作用轴线等概念。通过理论研究,解决反映螺纹装配实际作用效果的边界测量、螺纹截面轮廓特征的提取、测量误差修正和螺纹装配作用效果评定等关键问题。应用一种新的螺纹综合测量方法,为提高螺纹检测水平、完善螺纹检测体系提供新技术。本文主要研究内容如下:(1)提出螺纹作用边界测量理论与方法。对螺纹整体进行测量,建立以截面牙型轮廓为组成要素的轮廓特征提取模型,根据组成要素拟合导出要素,得到基准轴线,进而确定作用边界的位置与几何尺寸。(2)基于柔性机构设计理论,建立螺纹测头非刚体模型,确保测端能够实时、综合反映被测螺纹的轮廓特征;分析了测头测量误差源以及运动误差导致的测量不确定度。(3)针对一代样机测端结构,提出源于螺纹升角因素的误差补偿方法;发明一种消除螺纹升角影响的新型测端。(4)建立以测量仪转台轴线为基准的尺寸传递系统,提出一种测端快速标定方法。(5)实验验证测量仪的精密度与准确度;初步建立基于作用边界测量的螺纹综合评价体系,进行螺纹工件测量实验;根据误差源分析对整机进行不确定度评定。更多还原

【Abstract】 The screw thread is a complex geometric body.When the internal and external threads are assembled,it should be the contact of the spiral surfaces in theory.However,the actual threads have machining errors,and the expressions of their respective errors and the distribution in three-dimensional space are different.It is difficult to quantify the actual assembly effect.For the sake of simplicity,the actual thread is assembled with a virtual ideal thread,which reflects some characteristics of the actual thread after assembly.The thread standard ISO 5408: 2009 defines that the functional diameter is the pitch diameter of a virtual ideal thread that can fit the actual thread perfectly and does not interfere with the crests and the roots.In this paper,according to the definition of the functional diameter,the concepts of the functional boundary and the functional axis are proposed.By theoretical research,it solves key problems such as the measurement of the functional boundary,the extraction of the thread profile features,the correction of the measurement errors and the evaluation of the thread assembly effect.A novel comprehensive measurement method is applied to provide a new technology for improving the thread inspection level and perfecting the thread inspection system.The main research contents of this paper are as follows:(1)The measurement theory and method of thread boundary is proposed.The contour feature extraction model is established with axial sectional profile as the real feature by measuring the whole thread.The associated derived feature is obtained as the reference axis,and then the position and geometric dimension of the boundary are determined.(2)The compliant mechanism design theory is applied to establish the pseudorigid-body model of the threaded probe,which ensures that the measuring tip can comprehensively reflect the contour features of the measured thread in real time.The measurement error source of the measuring head and the measurement uncertainty caused by the motion errors are analyzed.(3)For the structure of the measuring tip on the prototype,the error compensation method of the lead angle factor is proposed.A new type of measuring tip is invented,which can directly eliminate the error source of the lead angle effect.(4)Establish a size transfer system based on the axis of the measuring instrument turntable,and propose a rapid calibration method for the measuring tip.(5)The precision and accuracy of the measuring instrument are verified by experiments;the comprehensive evaluation system of the thread based on the functional boundary measurement is preliminarily established,and the thread workpieces measurement experiments are carried out;the uncertainty of the measuring instrument is evaluated according to the error source analysis.更多还原