Research On Five-degree-of-freedom Errors Measuring System Of Machine Tool Worktable

With the development of modern high-tech industries,people's demand for precision and ultra-precision parts has risen sharply,and at the same time,higher requirements have been placed on the machining accuracy of machine tools.When the machine tool table moves along the guide rail,there are six degrees of freedom geometric errors,namely position error,two-dimensional straightness error,yaw angle error,pitch angle error and roll angle error.The precise measurement of the geometric error of the machine tool table is an important means to guarantee the machining accuracy of the workpiece.The traditional measurement methods are mostly single-parameter measurement.The measurement process is long and the accuracy is low.Obviously,it cannot meet the needs of modern industrialization.Therefore,the development of a set of multi-degree-of-freedom measuring equipment with high accuracy,low cost,small size,and large measuring range is of great significance for improving the machining accuracy of machine tools.In view of the problems existing in the traditional measurement methods of geometric errors of machine tool tables,this paper proposes a five-degree-of-freedom simultaneous measurement method based on laser collimation technology through a comprehensive analysis of the research status at home and abroad,using a semiconductor collimation laser as a light source,combined with spectrometry Precision optical lenses such as prisms,reflectors,and convex lenses form an optical path system.Four-quadrant detectors and position-sensitive detectors are used as sensitive components for error measurement to realize two-dimensional straightness,yaw angle,pitch angle,and roll angle of the machine table.Following the design principles of modularization,miniaturization and high integration,a five-degree-of-freedom simultaneous measurement system was built to meet the requirements of small size,high precision,large measurement range,and low cost.It mainly includes the selection of lasers,photodetectors,and optical lenses,design of pre-amplifier circuit,analog-to-digital conversion circuit,wireless transmission circuit,embedded program and host computer software design,mechanical design of fixed end and mobile end,etc.In order to improve the measurement accuracy,the main sources of error in the five-degree-of-freedom measurement system are analyzed,theoretically compensating the crosstalk error and laser angle drift error between the respective degrees of freedom,and the nonlinear error and non-measurement light pairs of the photodetector are explored due to the influence of the measurement results,solutions to reduce random errors such as electronic noise errors and mechanical installation are proposed.Finally,in order to verify the reliability and accuracy of the five-degree-of-freedom measurement system,a series of experiments were carried out on the measurement system under laboratory conditions,including calibration experiments,stability experiments,and comparison experiments.Analysis of the experimental results shows that within 60 minutes,the stability error of the straightness measurement is less than 1.2?m,and the stability error of the angle measurement is less than 1.5?;within a measurement distance of 1.5m,compared with the standard equipment,the comparison error of the straightness measurement less than ±2?m;the contrast error of angle measurement is less than ±4?.It is verified that the measurement system has good stability and accuracy,meets the requirements of precision measurement of machine tools,and the measurement range reaches the distance of meters,which has certain guiding significance for the measurement of the geometric error of the workbench of ultra-long stroke machine tools.