Key Technology Research On CNC Worm Grinding Of Modification Gear

Worm grinding is a continuous indexing finishing method for gear processing, theprocessing precision of which usually is ISO3-5. The development of high and newtechnology industry like automobile manufacturing, aerospace and wind powerequipment, draws the higher demands in gear processing. It requires not only higherprocessing precision but also the modification of the gear. Worm grinding which hashigh processing precision, high efficiency and good adaptation, is an importantprocessing method for medium and small module gear. At present, research anddevelopment of worm grinding in China started relatively late, especially formodification gear, and there is a larger gap in processing precision compared withadvanced foreign products. Special-shaped spiral surfaces spatial mesh whenmodification gear grinding. How to develop mathematical models, how to maketrajectory plan is great problem in worm grinding and it has a great influence on thegear precision. Therefore, this paper has a certain theoretical significance and a veryimportant practical application value. The main contents of this research are as follows:Firstly, mathematical models of gear with tooth profile modification is developed,based on two-parameter point vectors method, Tooth profile is dispersed in the methodand keeps the most geometrical information at the same time. The cross section ofworm grinding wheel is solved, with the help of computer, using numerical simulationto simulate grinding process. An algorithm that point vectors are dispersed in the sharppoints is proposed to reduce the error of transition surface when the sharp points occurto tooth profile.Secondly, a study on the axial modification of gear in worm grinding is made.There are three addition movements to finish the axial modification of gear, which arecenter distance changing, addition gear rotation and worm grinding wheel axialmovement; Trajectory planning is made, based on the three addition movement and therelationship between gear and worm grinding wheel in the worm grinding.Then, study on the pressure angle error and lead error in worm grinding, establishevaluating standard and find out the reason they exist. A new method is proposed tocompensate the pressure angle error and lead error in worm grinding.Finally, technological process of worm grinding is designed based on the demandof gear grinding and situation of the workshop. Software of worm grinding is developed based on Visual Basic6.0and Siemens840D CNC system. The software with humanmachine interface can real-time display machine data, store technological parameter andcommunicate with NC.