Geometric Error Modeling Of Ultra-precision Drum Roll Lathe And The Research On It's Compensation Algorithm

Micro-structured surface refers to special function surface which has micro topological structures,surface roughness to nanometer level,shape error to submicron level,only has a few or dozens of microns in shape size.It is widely used in the field of aerospace,energy,IT.Recent years with the popularity of smart phones and large size of LCD screens,the use of various types of optical microstructure films is increasing.RTR embossing technology stands out in many processing methods with its high processing efficiency,good quality,suitable for mass production and some other advantages.It is the most promising technology for large volume microstructure processing.As the core components of RTR processing technology,the quality of the microstructure on the roller mold surface will directly affect the quality of embossed film,so it has a very high demand for ultra-precision roller mold lathe.At present,the ultra-precision machining technology of roller mold is dominated by foreign countries,the price of its machine up to tens of millions of yuan.But domestic research in related fields has just started,there is a big gap between the domestic independent development of ultra-precision roller mold machine and abroad,the main reason is still in the processing accuracy.Geometric error as one of the most important error sources that affect the machining accuracy of the machine,it will directly lead to the actual trajectory of the tool from the ideal track and thus affects the quality of processing.In this thesis,we research on geometric error of lathe based on the first self-development ultra-precision drum roll lathe which is designed by our team,the purpose is to reduce the impact of the geometric error on the processing accuracy for imprinting high quality optical film.To this end,this article mainly contains the following aspects:Firstly,turn the mechanical structure of the machine into a topology using the lower body array of multi-body system,and then use the homogeneous coordinate transformation method to derive the geometric error model of the lathe in order to get the error expression of it in two linear axes,this provides the basis for subsequent compensation.Secondly,using the laser interferometer to measure the individual geometric errors related to the geometric error model.Taking into account that the actual processing process for different microstructure surface has different processing characteristics,two methods are proposed to compensate geometric error of the lathe in this paper,namely NURBS curve interpolation method and polynomial fitting-NC instruction correction method.Finally,in order to verify the feasibility of two compensation methods,ring groove microstructure array cutting experiment and free surface processing experiment were carried out respectively.From the test results,the compensation method proposed in this paper can significantly reduce the influence of the geometric error on machining accuracy,so that the quality of the microstructure surface on the roller mold is obviously improved.