Optimization method and experimental study on tooth spacing angle of variable pitch milling cutter based on eliminating additional damping

Chatter in milling processes seriously affects machining efficiency and machining quality. Variable-pitch cutters improve milling stability through irregular distribution of tooth spacing angles, which disrupt the fixed time delay and periodic excitation that cause regenerative chatter, thereby weakening self-excited feedback and dispersing vibration energy. To enhance the chatter suppression performance of variable-pitch milling cutters, an optimization method for the tooth spacing angles of variable-pitch milling cutters is proposed, with the elimination of additional damping in the milling system as the optimization objective. A milling dynamic model for variable-pitch cutters is established, and the corresponding stability analysis algorithm is introduced. Numerical simulation and milling test results show that the optimized variable-pitch cutter exhibits higher milling stability. At 5 950 r/min, the stability limit cutting depth of the variable-pitch cutter is increased from 1.405 mm (for the equal-pitch cutter) to 2.425 mm, representing an improvement of 72.6%. Under the critical transition conditions where the equal-pitch cutter experiences chatter while the variable-pitch cutter maintains stable cutting, the root mean square (RMS) value of vibration of the variable-pitch cutter is reduced by 66.7%-78.4%. The above results verify the effectiveness of the proposed method.