| Bevel gear transmission has strong load capacity,smooth transmission,compact structure and other characteristics,is the key components of vehicles,ships,machine tools,oil drilling,aerospace and other equipment power drive.In today’s rapid development of equipment electrification,gears are still regarded as irreplaceable transmission parts in mechanical systems.Bevel gears are usually used to plan teeth,double cutter milling and other spreading processing methods,these processing processing high efficiency,but the need to use special processing machine tools,high procurement costs,and more difficult to achieve the size specifications of the larger gear processing,less suitable for single-piece small batch production.Using the high flexibility of multi-axis machining centers,generalpurpose tools are used to solve the problem of processing small bevel gears in small batches and large sizes.However,the gear machining based on machining center usually treats the gear tooth surface as a free-form surface,which has a low material removal rate and makes it difficult to improve the machining efficiency;moreover,most of the current gear machining methods based on machining center are modeled on the theoretical tooth surface with line conjugation,which is prone to edge contact under load resulting in early failure of the gear pair.Therefore,there is an urgent need to study the bevel gear processing method based on the digital spreading principle to improve the efficiency of machining center gears,so that it can complement the traditional gear spreading processing technology using special machine tools.In this paper,we propose a small batch bevel gear machining method based on the digital spreading principle,which makes use of a universal tool and its trajectory motion to form a virtual production gear spreading into the machined gear,so that the tooth surface machining still maintains the spreading machining characteristics and significantly improves the machining efficiency while ensuring the tooth surface quality.According to the principle of spreading machining,the relative motion of the tool and the workpiece is analyzed and the tooth surface equation of the straight bevel gear is derived;by making reasonable tooth surface modification,a tooth surface modification digital model is established according to the principle of conjugate meshing to improve the system deformation under load and the degradation of edge contact meshing performance caused by gear meshing misalignment.The proposed method of first controlling the general-purpose disc milling cutter sweep to form a discrete virtual production gear on the machining center,and then controlling the virtual mesh of the virtual production gear and the gear to be machined to spread the gear tooth face,can significantly improve the machining efficiency.The mathematical model for calculating the tool position of bevel gear digital spreading machining is derived from the above principles,and the rough and finish machining toolpath trajectory planning is carried out to realize the efficient digital spreading machining of straight bevel gears based on disc milling cutters.The correlation between milling feed rate and cutting force,temperature and cutting force,and cutting force and tool life is established,and the idea of machining process optimization based on machining efficiency and tool life is proposed,and the bevel gear machining method based on digital spreading principle is optimized using Production Module 3D with cutting force as the main line.The paper implements the digital spreading principle based bevel gear tooth profile and its milling toolpath planning,and develops the corresponding algorithm program based on the relevant theoretical method.The expected results of this paper will effectively solve the current core technology bottleneck of machining center gears,expand the functions of machining center,and provide new technical ideas for the processing of small batch bevel gears. |
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