Non-circular Helical Gear Cnc Hobbing Key Technologies

Fixed transmission ratio gear is made up of cylindrical spur gear and cylindrical helical gear. Similarly, variable transmission ratio gear is composed of non-circular spur gear and non-circular helical gear. So far the study of the non-circular spur gear has been already more perfect, but non-circular helical gear, confining to its calculation of tool outline mainly, though some scientific researchers have researched its machining, but not perfect. The research works in this dissertation is carried to make a breakthrough, which is important, both for the development and practical application of the gearing technology.In this dissertation, the reason why the traditional gear-hobbing machine is unfit for hobbing non-circular helical gears is analyzed.On the base of the meshing theory of helical gears and tool rack-skew methods, four simultaneous-control methods of CNC for hobbing non-circular helical gears are proved. Especially, the reason why there is the additional rotation speed is explained. The 4 or 5 axis simultaneous-control relation is formulated.Something about the variable speed ratio electronic gearbox has been more systematically studied, included structural forms, precision following, systematic optimization design, control strategy, etc. At the same time four transmission methods are worked out, which are connected with the former simultaneous-control relation.Elliptical, hyperbolic and parabolic interpolation algorithms are introduced in this dissertation, which are based on central angle division. At the same time, the arc-length of ordinary and higher order ellipse are calculated. Finally, the equal arc length algorithm and the equal angle algorithm are introduced.When a work piece is hobbed or when gear profile is modified by CNC gear-hobbing machine, the coordinate calculation of cutter-setting position is very important because it will effect the machining accuracy and the complexity of CNC programming, and so on. At the present time there is few documents or papers that have introduced the accurate calculation. In this dissertation the coordinate calculation is done perfectly, which is included cutter-setting position about cylindrical spur gear, small cone angle gear, drum corrected gear.