基于球头铣刀的弧齿锥齿轮小轮铣削加工方法研究

Milling method of pinion of spiral bevel gear based on ball end cutter

弧齿锥齿轮小轮铣削通常在专用机床上采用铣刀盘实现,从而导致制造成本较高。为了降低弧齿锥齿轮小轮的制造成本,提出一种在通用四轴数控铣床上采用球头铣刀进行铣削加工的方法。根据齿面数学模型计算齿面离散点坐标,进而创建齿轮实体模型。分析齿根铣削时球头铣刀与齿轮的空间位置关系,以铣削一侧共轭齿面时不刮伤对侧共轭齿面为原则确定球头铣刀直径。以刀杆与齿面不发生干涉为前提,确定处于各个加工位置时的刀轴方向。以沿齿高和齿长方向均匀分布的齿面离散点为基础,创建沿齿高方向分层的粗铣刀路和沿齿长方向分层精铣刀路。创建包含机床、刀具和轮坯的仿真加工环境,完成齿轮铣削仿真。结果表明:相比于铣刀盘,球头铣刀加工得到的过渡曲面曲率半径更大,可降低齿根处的应力集中程度。将刀路导入数控加工系统,在四轴数控铣床上完成齿轮的粗铣和精铣,获得的齿面具有较好的光洁度,从而验证了本方法的可行性。

milling process of pinion of spiral bevel gear is generally realized by special purpose machine and assembled milling cutter,which leads to high manufacturing cost.A method of milling pinion of spiral bevel gear is proposed based on universal four axis CNC milling machine and ball end cutter in order to reduce manufacturing cost.Discrete points of gear surface are calculated based on mathematical model and solid model of pinion is created.In order to avoid tooth root over-cutting,diameter of ball end cuter is determined by analyzing geometrical relationship between tooth root and ball end cuter.Directions of cutter axis are calculated to avoid interference between tooth surface and ball end cuter.Tool paths of rough and fine milling are created based on discrete points which are distributed evenly on depth and length direction of tooth surface.Simulation cutting environment is established including machine tool,cutter and gear blank.When simulation cutting process is completed,the result of simulation cutting shows that radius of curvature obtained by ball end cuter is larger than obtained by assembled milling cutter,which can reduce stress concentration of tooth root.Tool paths are imported into CNC system,milling process is realized on four axis CNC milling machine and tooth surface with high quality is obtained,which indicates milling method mentioned above is feasible.