The Research Of Non-Circular Gear Error Measurement Method Based On Arm Laser Scanner

The compact structure and high reliability are the non-circular gear's advantages.The non-circular gear is widely used in light industrial production.Currently,the non-circular gear measurement is a research hotspot and a research difficulty.However,the development of circular gear is earlier,the error measurement method is more perfect and the accuracy testing index is also more comprehensive.Therefore,it is necessary to establish the non-circular gear precision index based on the precision index of the circular gear.To improve the machining accuracy of the non-circular gear is of great significance.This paper aims at the non-circular gear's accuracy measurement.According to the study of the machining error of non-circular gear,the non-circular gear error is classified as well as the articulated arm scanner is used to acquire the non-circular gear 3D point cloud model.And then the 3D test model is aligned with the theoretical model and analyzes the error of non-circular gear.Finally,the known accuracy of the circular gear is scanned to obtain the error of the five mandatory test items.The non-circular gear's error is analyzed by comparing the measured error with the allowable value in the new gear standard ISO 1328-1.First of all,according to the machining principle of non-circular gear,a non-circular gear hobbing model is established to analyze the error caused by the rotation of the workpiece,the horizontal movement of the rack,geometric eccentricity and machining tool.On the base of the machining error,the error items of the cylindrical gear are compared and the error of the non-circular gear is classified.Secondly,the theoretical three-dimensional model of the non-circular gear is established.The convert profile method and gear profile normal method are used to establish the 2D drawing and analyze the two method.The model error coefficient “k”is introduced to improve the theoretical model's accuracy of the non-circular gear.On the base of the established model,the non-circular gear is scanned by the Arm Laser Scanner to obtain a three-dimensional test model.and the three-dimensional test model is aligned with the theoretical model.Multiple alignment methods are provided for the alignment of the model when the Geomagic Qualify data processing software is used.The tooth thickness error is measured and the comparative analysis shows that the “based on feature and best-fit alignment method” is more accurate.After themodel is aligned,according to the error definition of the non-circular gear,the pitch error,tooth profile error and tooth error of the non-circular gear are measured,which lays the foundation for the establishment of the non-circular gear precision indicators.Finally,the old and new standard of circular gear are compared and the tolerance calculation formulas for non-circular gear mandatory inspection items are analyzed.The circular gear is scanned by the arm laser scanner and obtain the point cloud data as well as the error values are compared and analyzed.The error values measured by the new method are compared with the tolerance values defined by the national standard and then establish the accuracy index of the non-circular gear.The establishment of accuracy of the circular gear provides a way of thinking about the establishment of the non-circular gear's accuracy.After the research of this topic,a new non-circular gear error measurement method named joint-arm scanner measurement method is proposed.Through the use of this method,the measurement speed is improved.On the base of the obtained error,the non-circular gear precision index is analyzed by comparing the national standard tolerance and the measurement error,which provides a reference for the establishment and improvement of the accuracy of the non-circular gear in the future.