Study On Parameter Optimum Design Of Quasi-Plane Double-Enveloping Hourglass Worm Gears

To solve the problem that the two sides helicoids of planar double-enveloping hourglass worm can't be grinded simultaneously, the quasi-plane double-enveloping worm is put forward.It makes use of the characteristic that conical face is similar to plane in local region when it has a larger radius and conical angle. The worm is generated by a large diameter and conical two-sided symmetry conical grinding wheel. However, only when the parameters are chosen properly, this kind of worm drive can have the same performances as planar double-enveloping hourglass worm gears and cover the shortage existing in the processing property of planar double-enveloping hourglass worm at the same time.In this paper, the meshing theory of quasi-plane double-enveloping hourglass worm is systematically established with the moving coordinate method. Based on this, the calculational methods of axial crest width at the end of worm and helix angle are deduced, then the grinding wheel's correct parameters and installation positions are designed. A theory foundation above is built for the parameters analyzing and optimizing.It is concluded that the effect rules of every parameters are different after the effect rules of some primarey parameters to geometry characteristics and meshing performances are discussed, so an overall optimization must be given for proper geometry characteristics and meshing performances. The geometry characteristics including"topping"of the worm's side teeth and"undercutting", the mesh performances including the contact line distribution and lubricating angle.The optimizing variables are chosen and the optimizing object function as well as the bound for objective function are set up based on its own characteristic.of the quasi-plane double-enveloping hourglass worm. Considing two conditions of"common drive ratio"and"multi-thread and low-speed"together, the complex method is improved to reduce calculation of the object function and the bound for objective function. Then, taking this for example, the results show that this optimizing method can successfully solve the problem that how to choose the design parameters in condition of"common drive ratio"or"multi-thread and low-speed". The method has a high presion and is suitable for wider range transmission ratio. Furthemore, it can solve complex problems by a simple optimizing idea. Finally,a set of worm gear is designed and processed after the parameters being optimized, then a performance experiment is conducted. The results show that this type worm drive can be manufactured easier and has equivalent load capacity than planar double-enveloping hourglass worm. It has high transmission efficiency and low temperature rise. So it is high possible for this optimizing method to use in practice.