Research On Ultra-Precision Measuring Straightness And Surface Microtopography Analysis

Ultra-precision machining is an important factor of advanced manufacturing technology, on the other hand, it is a complex advanced technology synthesized many techniques which involve machining methods, material, machining tools, technics, measuring methods, environment , arts of operators and so on. The mainbody of this dissertation are measuring method for ultra-precision straightness, modeling the surface topography of ultra-precision turning, analyzing the characteristic of workpiece surface and error identification. Its contents include several aspects as follows.1. Measuring methods of ultra-precision straightness. Some scanning probe methods which include two points method, three points method and the mixed method which employs two scanning probes and one angle probe, and the errors separation methods which can separate workpiece straightness from straightness motion error of the scanning stage are used in precision machining widely. Some methods are needed to be adopted to separate the yaw error of scanning stage when it can't be ignored. This dissertation bring forward a novel method which employs autocollimation and scanning probes. The straightness profile of workpiece can be measured, and the straightness motion errors of scanning stage can be separated precisely.2. The exact reconstruction theory of ultra-precision workpiece straightness. The existing error separation technology based on scanning probe method are all approximate arithmetic, and mostly assume a priori knowledge or only adapt to measuring some special profiles. For more than 20 years, some methods have been developed for these cases of difference measurements, but all these methods cannot exact reconstruct straightness of arbitrary workpiece. This dissertation suggests two methods are named frequency domain method and time domain method. Both can solve this problem. Besides being applied in measuring straightness, these two exact reconstruction methods also can be applied in shearing interferometry. As a consequence, shearing interferometry can hope to compete with the established interferometric methods based on the use of a reference wave.3. The technology of surface topography modeling and simulation for ultra-precision diamond turning. Based on machine kinematics and cutting theories, the simulating method for the generation of three-dimensional surfaces in face turning and flycutting of SPDT is studied. Some problems existing in literature are solved. The model can be used for simulating the locus of tool motion, predicting the surface topography and the characteristic of section profile, and this simulating model also can help to determine the optimal cutting conditions without the need for costly trial-and-error cutting tests.4. Analyzing the characteristic of workpiece surface. Taking into account the ratio between the relative tool-workpiece vibration frequency and the spindle rotating frequency, the phenomena of tool interference, this dissertation analyzes the characteristic of workpiece surface topography more completely. And various factorswhich affect the characteristic of section profile are considered. The frequency characteristics of radial, circumferential and spiral section profile are analyzed in theory using Fourier transforms.5. The method of error identification. Based on the model of surface topography, this dissertation solves the problem of identifying the frequency of relative tool-workpiece vibration in theory. Two methods of spiral and radial-circumferential analysis using surface data are proposed.