Research On High Precision Zero-point Positioning Device For Processing And Transposition Of Precision Micro Parts

Miniaturization of mechanical parts is a current research trend.Miniature parts have the advantages of small occupied space,low energy consumption and material saving.These parts are often used in key systems such as aerospace instruments,nuclear industry,micro-engine nozzles,etc.Most of them are parts with complex shapes and great processing difficulty,and require multi-process processing and multiple clamping.However,the error control in the multi-process processing of complex precision microsmall parts has not been completely solved,and the influence of re-clamping error and processing cutting force cannot be ignored.In order to effectively control the error value in the processing transposition operation of such parts,it is necessary to adopt a zeropoint positioning device with high positioning precision.However,most of the existing devices are large in size and are mostly used in the production of common processing precision to improve the processing efficiency,and their precision indexes cannot meet the application requirements in the ultra-precision field.Therefore,it is necessary to study a small zero-point positioning device with high precision and rigidity to control the precision forming process of precision micro parts.Based on the design principles and methods of domestic and abroad products,the design and research of high-precision and fast following positioning principles are carried out.According to the technical indexes and functional requirements of the project,highprecision positioning and clamping scheme design is carried out,two design schemes are obtained,and the two design schemes are checked and calculated.After analyzing and comparing their respective shortcomings,choose the appropriate scheme according to the requirements of the project to obtain the final design scheme.In order to realize the most important precision technical index of the device,it is necessary to analyze the error situation in detail.Firstly,the various error factors in the part processing process are analyzed and the clamping error is controlled.According to the positioning mode of the device,the positioning error value generated in the positioning process is calculated according to types,and the tolerance design of the positioning parts is carried out according to the technical index requirements,so that the overall error value meets the requirements.Mechanical simulation analysis is an important way for design optimization.Firstly,the rigidity of the design device and 3R device is analyzed,and the design is improved to effectively improve the rigidity of the design device.According to the calculated clamping force,the deformation and stress distribution of the parts under the working condition of the device are calculated to ensure that the device can normally work in use.Finally,the cutting force is calculated and the influence of various forces on the machining accuracy of the work-piece is analyzed,to guide the selection of processing parameters.In order to obtain the technical index of the device,the precision measurement test is first carried out.Using the designed experimental principle and the built device,the accuracy of the two devices were measured respectively.The feasibility of the experimental scheme was obtained by comparing the measurement results of an existing device with the nominal results.The designed device was measured,and the accuracy met the project requirements.The stiffness values of the System 3R zero-point positioning device and the design device are measured by using the set-up device.Compared with the results of calculation and analysis,the stiffness of the design device is better than that of the System 3R zero-point positioning device,and the causes of errors are analyzed.Finally,the functional feasibility of the design device is verified on the ultra-precision five-axis machine tool and measurement device to meet the use requirements.