The Compensation Method Research On Flank Twist During The Special-shaped Spiral Surface Worm Wheel Grinding

Worm wheel grinding is the main method during hard gear tooth processing, the processing precision of which is usually ISO3-5. The gear flank that modified in tooth orientation calls special-shaped spiral surface, which will produce inevitably twist in the process of worm wheel grinding, studies show that flank twist will cause gear side clearance becomes large, increase larger impact, vibration, working noise, reduce transmission precision and other issues. Now, the automotive, wind power, aerospace and other industries clearly put forward the control and compensation function of flank twist. The flank twist problem directly affects the quality and performance of the domestic gear grinding machine, which is a core problem that needs to solve. The problem of flank twist during worm wheel grinding will be deeply discussed in this paper. Therefore, this paper has a certain theoretical significance and a very important practical application value. The main contents of this research are as follows:Firstly, the research status of worm wheel grinding is introduced, the mathematical characteristics analysis of the special-shaped spiral surface is made, and a mathematical models of special-shaped spiral surface is developed. According to correspondence between the amount of modification and tooth thickness, the relationship between gear tooth thickness at different positions and the modification curve is calculated, and then, calculate center distance changing, addition gear rotation and worm grinding wheel axial movement; Trajectory planning of worm wheel is made based on the three addition movements in the process of worm wheel grinding, which are center distance changing, addition gear rotation and worm grinding wheel axial movement.Secondly, the space meshing characteristics of worm grinding is analyzed, a study of the mathematical characteristics of the meshing line and contact mark is made during the crisscross axis helical surface space meshing. According to the same amount of grinding on one contact mark, the mathematical models of twist is developed during the mesh between special-shaped spiral surface and worm, and then a method for optimizing modification curve to compensate for the twist of tooth surface is proposed and validated.Finally, a method of worm wheel dressing is proposed for flank twists, the module of flank twist compensation for worm wheel grinding machine is developed based on Siemens 840D-sl CNC system, which includes four parts, first, the calculation and display of tooth surface twist at each point on the gear flank; second, the comparison to normal tooth surface and the twist flank; and third, the optimization design of modification cave to compensate the tooth surface twist; last, the worm wheel grinding process design for flank twist compensation.