Research On Key Technology Of In-situ Measurement On Ultra Precision Lathe

Complex optical surfaces have special geometric shapes.Its outstanding performance in the realization of special optical properties makes it possible to simplify the overall structure of the optical system and enhances the quality of imaging and other aspects.At present,SPDT technology is a common method for machining complex optical surfaces.However,it is difficult to achieve the required surface accuracy and surface roughness in one processingfor its complex geometry.In actual processing,it is necessary to detected the surface accuracy,and the compensation process is repeated until the accuracy is obtained.Most of the optical measurement technology of complex optical' surfaceare belong to off-line measurement,which inevitably introduces positioning error.On the contrary,in-situ measurement can directly detect the surface of the machined parts without removing them,thus avoiding the problem of positioning error.Therefore,it is necessary to develop an in-situ measurement system,which isused for ultra precision lathe.The major contributions ofthis paper can be summarized as follows:1.In order to meet the high performance requirements of air float rails,an air static lubrication model(ALM)with small hole throttling is proposed based on the finite difference method.Through the combination of flow error feedback and grid parameter optimization,the numerical model is solved,the static characteristics of the bearing are obtained,and the bearing structure such as aperture diameter,quantity and position is optimized.Finally,the static performance of the linear guide rail is tested,and the conclusion is drawn that the theoretical results agree well with the experimental data.2.In this paper,the error sources of the in-situ measurement system are analyzed.From the point of view of error compensation,the correlation properties,the regularity and the influence of the measurement accuracy are obtained,and the process of the mutual relations between the errors is obtained.Through the modeling of the geometric motion errors,the transmission rules between the errors are obtained.3.The in-situ measurement system baseazd on Cartesian coordinate measurement principle is established.Meanwhile,the measurement accuracy of the in-situ measurement system is obtained.Meanwhile,the main errors that affect the accuracy of the in-situ measurement system are separated and measured.the straightness of the whole stroke of the guide rail is obtained.