The Comprehensive Measuring Instrument For Global Sizes And Geometrical Errors Of Two Parallel Opposite Planes

Two parallel opposite planes are the features of mechanical parts,and their sizes and geometric accuracy have an important influence on the quality and performance of mechanical parts.For two parallel opposite planes,in addition to two-point sizes,the new generation Geometrical Product Specifications(GPS)specifies global dimensions and geometric tolerances.The global sizes include least square sizes,minimum circumscribed sizes,maximum inscribed size and minimax size.Geometric tolerances include flatness tolerance and parallelism tolerance.In order to ensure the quality of products,it is necessary to measure the global sizes and geometric errors of the two parallel opposite planes.At present,there is no report on the measurement instruments related to the global size and geometric errors of the two parallel opposite planes.Based on the parallel profile extraction strategy,the related problems in the development of the comprehensive measuring instrument for global sizes and geometric errors of two parallel opposite planes were studied in this thesis.According to the specifications,structural characteristics and accuracy requirements of the two parallel opposite planes,the mechanical structure and control system of the measuring instrument were designed.The measuring instrument adopted the overall framework of double columns,double arms,double probes,one-dimensional workbench and base.The aerostatic guideway was composed of a horizontal arm composed of a granite column and an air floating block,and the probe moves up and down.The up and down movement was driven by a servo motor through a synchronous belt,and a linear displacement grating sensor was installed.The one-dimensional worktable adopted the linear guide composed of granite and air flotation block and the motion mode driven by linear motor.The horizontal arm adopted the modular structure driven by synchronous belt,installed linear displacement grating sensor and high precision inductance sensor,and adopted contact measurement.On the basis of the mechanical structure design,the overall design of the measurement and control system of the measuring instrument and the parameters of the configured motor and its driver,inductance sensor and linear displacement grating sensor,the computer program of the left and right movement,up and down movement of the double horizontal arm and sampling of the double probe was compiled to meet the needs of the profile extraction of two parallel opposite planes elements.The designed mechanical,measurement and control parts were manufactured and purchased,and the measuring instrument parts and main host were assembled.After inspection,the straightness error of the up and down movement of the two horizontal arms was 1.03 μm,the parallelism error of the up and down movement of the two horizontal arms was 1.94 μm,the straightness error of the one-dimensional workbench was 1.67 μm,the repetitive positioning accuracy of the up and down,left and right movements of the horizontal arms was 0.75 μm,and the repetitive positioning accuracy of the one-dimensional workbench was 0.75 μm.The dimensions of the measured two parallel opposite planes parts are : x,y and z directions should be less than or equal to 240 mm,450mm and 450 mm respectively.The measurement and control system were integrated with the measuring instrument feature,and the measuring instrument was debugged.The parallel profiles of the plane features of a two parallel opposite planes sample was extracted and the global size,flatness error and parallelism error were evaluated.The extraction and evaluation results showed that the parallel profiles extracted by the developed measuring instrument has the characteristics of high reliability and high accuracy,and achieves the function and accuracy requirements of the comprehensive measuring instrument for global sizes and geometrical errors of two parallel opposite planes.The main error sources of the measuring instrument were analyzed.The measurement uncertainty of the measuring instrument was evaluated.In this thesis,the development of a comprehensive measuring instrument for global sizes and geometric errors of two parallel opposite planes and related problems were studied.The high-precision measurement of global sizes and geometric errors of two parallel opposite planes may promoted the application of global sizes and geometric errors in two-phase plane parts.