Research On Measuring Method Of Alignment Of Double Helical Gears

After double helical gears are applied to heavy helicopter main gearboxes,naval power transmission systems and large energy power machinery,the requirements for manufacturing accuracy of double helical gears are much higher than when those were previously applied to open transmission occasions.The standard system of common helical gears is still used for measuring and evaluating the accuracy deviation of double helical gears.In order to describe the manufacturing accuracy and performance of double helical gears more comprehensively and accurately,the measurement method of double helical gears alignment deviation,including the definition of alignment deviation,measurement principle,measurement software development and measurement experiments is presented in this research,which provides a new measurement and evaluation method to comprehensively and accurately evaluate the accuracy of double helical gears,and has important guiding significance for the design and manufacture of high-precision double helical gears.Firstly,the definition of V-shaped apex of double helical gears in the sense of metrology is presented in this research,which includes two definitions of V-shaped apex based on contact line and helix line.The definition of V-shaped apex based on contact line can better reflect the working condition of gear pair meshing,but there are many problems in the measurement and evaluation of contact line;the definition of V-shaped apex based on spiral line can,to a certain extent,also reflect the working condition of gear pair meshing,and the spiral line of gear is easy to measure and evaluate,and it is easy to adjust and control in the manufacturing process.Secondly,the accuracy indexes and evaluation methods such as the individual alignment deviation,adjacent alignment difference,total deviation of alignment and symmetry deviation of V-shaped apex of double helical gears are given with reference to other accuracy indexes of gears.On this basis,the full helix measurement method and four-section pitch measurement method of alignment deviation are studied,in which the full helix method is to measure the helix of double helical gears left and right hand helical gears tooth by tooth.The measured data include the helix error of the measured tooth surface and the circumferential and axial information in the indexing cylindrical surface of each tooth surface,and the least square midline of the measured helix is obtained according to the measured data in the evaluation interval.The alignment deviation of double helical gears can be obtained by calculating the intersection coordinates of the least square midline of left and right hand helical gears.In the four-section pitch method,four cross-sections are selected to measure the pitch in the axial direction of the double helical gears,and four groups of measured data can be obtained on the same side of the tooth surface.The straight line equation of the two-point connection line on one side of the gear tooth surface can replace the least square midline in the full helix method.Similarly,the alignment deviation of double helical gears can be obtained.The software for measuring the alignment deviation of double helical gears was also developed based on the gear measurement center.Finally,the alignment deviation proposed in this paper can be accurately measured through measurement experiment research,which provides a new measurement and evaluation means for studying and analyzing the manufacturing accuracy and service performance of double helical gears.The experimental comparison of the two measurement methods shows that although the full helix method meets the definition of alignment deviation and has good repeatability for multiple measurements,the tooth by tooth measurement of helix is inefficient;the four-section tooth pitch method has a slightly larger measurement uncertainty,but the measurement efficiency is high,which is a suitable and efficient alignment deviation measurement method for industrial sites.