T样条曲面加工误差在机检测与补偿关键技术研究

发布时间：2018-03-16 13:49

本文选题：加工误差　切入点：在机检测　出处：《浙江大学》2015年博士论文　论文类型：学位论文

【摘要】：自由曲面零件越来越广泛的应用对自由曲面的精密化制造提出了更高的要求,传统的自由曲面加工误差检测与补偿方法中间过程需要进行工件的转移、重复装夹定位等繁琐操作,在数字化制造技术快速发展的今天逐渐显示出其不足之处。而在另一方面,在机检测技术的出现允许在加工机床上直接对工件进行检测,很好地避免了传统方法中大量的辅助时间和重定位等问题,但同时也提出了新的挑战。检测的精度和效率是自由曲面检测中的主要要求,由于在机检测过程占用了机床的加工时间,因而自由曲面的在机检测相比于离线检测对效率的要求更为严苛。本文针对自由曲面在机检测的特点,提出了一套高效的自由曲面的加工误差在机检测与补偿方法。利用加工曲面的在机检测数据和镜像补偿模型对设计曲面的控制顶点进行调整分别得到加工曲面和补偿曲面,实现对自由曲面加工误差的在机检测与补偿。本文主要完成了以下几项工作。1.提出多点约束下T样条曲面的重建方法,建立了T样条曲面重建中控制顶点的迭代调整流程。首先研究了单点约束下T样条曲面的重建方法,基于约束优化方法对T样条曲面上与约束点相联系的控制顶点进行调整,实现了单点约束下T样条曲面的重建。然后分析了多点约束下T样条曲面控制顶点调整过程中的相互重叠问题,通过迭代调整过程使得设计曲面发生变形,最终完成对所有约束点进行拟合。2.针对自由曲面控制顶点的作用域,提出了一种基于曲面敏感点的采样点选择方法。首先,对自由曲面控制顶点对曲面的贡献进行了分析,针对多点约束下自由曲面的重建方法提出了基于曲面敏感点的采样点选择方法。针对带关键区域的自由曲面检测提出了基于T样条曲面的采样点局部细化方法。基于曲面敏感点的采样点选择方法结合T样条曲面的局部细化能力实现了自由曲面检测中采样点的局部细化,可以根据曲面不同区域的优先级别设置不同密度的采样点,有利于提高自由曲面检测的效率,达到检测资源最大化有效使用。3.针对传统的自由曲面加工误差检测中需要进行工件转移、重新装夹定位等问题,提出了基于曲面控制顶点调整的曲面加工误差在机检测方法。该方法结合了多点约束下自由曲面的重建理论,可以通过对相对少的采样点检测完成曲面加工误差检测与评估,提高了自由曲面加工误差在机检测的效率。4.针对带关键区域的自由曲面各区域检测与加工精度的要求不同,提出了一种带关键区域的自由曲面加工误差检测与补偿方法,利用T样条曲面对曲面关键区域进行采样点细化,提高了曲面关键区域的检测与补偿精度。首先利用T样条曲面的局部细化对曲面的关键区域进行细化,采用基于曲面敏感点法的采样点选择方法对曲面的采样点进行选择,在曲面的关键区域配置更多的采样点,提高曲面关键区域的重建精度,实现对曲面关键区域更高精度的加工误差检测与补偿。5.在理论研究成果的基础上,通过具体的自由曲面加工实验对所提的自由曲面加工误差在机检测与补偿方法进行了验证。首先,通过对一张NURBS曲面的加工、检测与补偿验证了基于自由曲面控制顶点调整的曲面重建方法在自由曲面加工误差在机检测与补偿的有效性。然后,对一张带关键区域的T样条曲面进行加工实验研究,采用基于曲面敏感点的采样点选择方法,利用T样条曲面的局部细化性质对加工曲面在机检测的采样点进行局部细化,实现了对曲面关键区域更高精度的加工和检测,并通过CMM检测对实验结果进行了验证。
[Abstract]:Put forward higher requirements of precision manufacturing of free-form surface parts are applied more and more widely on free surface, free surface machining error detection and compensation method of the traditional process to transfer the workpiece, repeated clamping and positioning and other complicated operation, with the rapid development of digital manufacturing technology today has gradually shown its shortcomings. On the other hand, in the presence of machine detection technology allows the machine to detect directly the workpiece, a good way to avoid the problem of the traditional method a lot of auxiliary time and relocation, but also put forward new challenges. Are the main requirements for free surface detection in the detection accuracy and efficiency. In the process of the testing machine used for processing time machine, and free surface in machine detection compared to the offline detection efficiency of the more stringent requirements. Aiming at the free surface in the machine. The characteristics of machining error are put forward a set of effective free surface in machine detection and compensation method. By using surface processing in machine detection data and image compensation model of control points of the design surface adjustment of machined surface and compensation surface were obtained, the machining error of free-form surface in machine detection and compensation reconstruction. This paper mainly completed the following work.1. proposed multi point constraint T spline surfaces, an iterative adjustment process control points of T - spline surface reconstruction. Firstly studies the reconstruction method of single point constrained T spline surface, adjust the control points of the constrained optimization method is linked to the T spline on the surface and based on constraint points, realized the single point under the constraint of T spline surface. And then analyzes the multi point constraint T spline overlap problem vertex in the process of adjustment of surface control, by Diego Generation adjustment process makes the design surface deformation, the final completion of all constraints by fitting.2. according to the scope of free surface control points, this paper puts forward a method based on surface sensitive points of the sampling points. First, on free surface contribution to the surface control points are analyzed, aiming at the reconstruction of free-form surface points under the constraint of the selection method of surface sensitive points. According to the sampling point based on detection of free surface with key region of the proposed sampling point local refinement method based on T spline surface. Surface sensitive point sampling point selection method based on T spline surface local refining capacity to achieve the local refinement of sampling points in the detection of free surface based on the sampling points can be set according to different surface area density of different priority level, can improve the efficiency of free-form surface detection, to detect the resources In the effective use of.3. for the workpiece transfer error free surface processing of traditional detection, re positioning clamp mounting problem, put forward the error surface machining surface control points based on machine detection method. This method combines the theory of free surface reconstruction of multi point constraints, can complete the detection and evaluation of surface machining the error of sampling points less detection, improve the machining error free surface.4. efficiency in machine detection requirements for the free surface with key areas of the region detection and the different machining precision, a new method of free surface machining with key area detection and compensation method, using T spline surface facing the critical region sampling point refinement, improved detection and compensation accuracy of key area surface. Using local refinement of T spline surface area on the surface of fine key Using surface sensitive point method, sampling point selection method of sampling points on the surface were selected based on sampling points, in key areas more surface configuration, the key to improve the regional surface reconstruction precision, realize the machining error of the critical area surface more accurate detection and compensation in.5. on the base of theoretical research. Through the experiment on the free surface machining error free surface machining proposed in machine detection and compensation method is verified. Firstly, through the processing of a NURBS surface, detection and compensation to verify the effectiveness of the error free surface in machine detection and compensation of the freeform surface reconstruction method based on control points then, experiments were carried out to study the processing of a key region of the T spline surface, using surface sensitive point sampling point selection method based on using T spline surface local refinement The local refinement of the sampling points for machine surface detection is done based on the property, and the machining and detection of the key area of the surface is processed with high accuracy. The experimental results are verified by CMM detection.

【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TH161.1

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