NC Machining And Tool Path Optimization For Recess-free Double Helical Gear

Double helical gear, consists of left hand helical gear and right hand helical gear, is used in heavy duty mechanical transmission because it have strong carrying capacity and can transmit power stably without axial load. In traditional machining process, double helical gears are machined by hobbing and grinding. Engineers have to design a recess in the middle of the gear to avoid interference. This recess increase the width of the gear, bring negative impacts to the alignment of gear teeth and compactness of gearbox. In this paper, 5-axis CNC machine and flank milling method has been used to manufacture recess-free double helical gear, which has better teeth alignment and bending strength. This method has an advantage over small amount, different specifications manufacturing plan compared to the traditional method.Machining of recess-free double helical gear has been studied in this paper, machining precision has been ensured and efficiency has been improved. The machining process, optimal tool path and secondary development for optimal tool path have been studied based on CNC machining technology, constant scallop height method and flank milling theory. The main works in this paper can be concluded as follows:1. The machining process for recess-free double helical gear has been designed, machining parameters and tools has been chosen according to it.2. The NC machining program has been designed by using UG software, the optimal tool path for final machining has been calculated based on constant scallop height method, w h i c h s h o rt en t h e t o o l p at h.3. A program, which can generate the constant scallop height tool path, has been designed based on UG software secondary development.4. The correctness and the effectiveness of NC machining program has been verified by using VERICUT software.5. The recess-free double helical gear has been manufactured in 5-axis CNC machine, then it has been measured in gear tester. It’s proved that the precision of the gear meets the design requirements, and the constant scallop height tool path can save lots of machining time.In conclusion, this paper provide new solution for the manufacturing of recess-free double helical gear and the design of new type double helical gearbox.