Abstract:  To address the challenge of aligning the grinding wheel with the entry point during multi-head thread grinding, where the grinding wheel returns to zero point and waits for a revolution signal while the spindle rotates through a deflection angle, and affects the interpolation efficiency, a rapid threading algorithm was devised based on a hybrid asymmetric polynomial acceleration-deceleration control. Firstly, the principles of thread threading and grinding wheel entry methods were analyzed to identify the critical entry point selection characteristics. Then, a zoning-based interpolation time planning model was established, and a pulse time variation model was formulated to align the grinding wheel with each entry point based on the interpolation planning and entry point selection features. Subsequently, a hybrid asymmetric polynomial acceleration-deceleration control model was designed, incorporating the fundamentals of fifth-order and third-order velocity curve control algorithms, along with a parameter control model and a target speed prediction model for the rapid retreat zone. Finally, MATLAB simulations were employed to validate the correctness and effectiveness of the proposed multi-head thread rapid threading algorithm. The research results show that under conditions 1 and 2(the number of thread heads is 20 and 25 respectively, other conditions are the same), the processing efficiency respectively increases by 12.98% and 0.67% for sequential and symmetric entry methods, with the optimal method determined by the operating parameters. Furthermore, the variable accelerationdeceleration control achieves a tolerance control of ±4 ms in the deceleration segment of the rapid retreat zone, reducing the tolerance pressure on the grinding wheel-entry point alignment. The hybrid asymmetric polynomial accelerationdeceleration control algorithm can enable flexible interpolation and flexible control of jerk, enhancing the efficiency of multi-head thread threading.
Key words: multiple thread split algorithm; quintic velocity curve; cubic velocity curve; interpolation time planning; screw thread entry point; hybrid asymmetric acceleration and deceleration control algorithm; parameter control model