Meshing performance investigations of involute worm and helical gear drive based on counterpart rack

Due to the involute worm and helical gear drive is different from the parallel shaft helical gear drive and the worm drive, the plane meshing theory and the space enveloping principle cannot be directly applied for this worm drive when the meshing analysis is performed, there has been no good analysis method to accurately calculate the meshing situation. To satisfy the increasing requirements of low-noise and long-lifetime in the service robots and the modern intelligent house systems, especially the intelligent shading system in the modern intelligent house system, a novel meshing performance analysis method is proposed for the involute worm and helical gear drive based on the counterpart rack. By calculating the contact line between the counterpart rack and helical gear and the contact line between the counterpart rack and involute worm, we can get the contact point of involute worm and helical gear finally. This novel meshing performance analysis makes it possible to use the plane meshing theory and the space enveloping principle to analyze involute worm and helical gear drive. The meshing relationship between the involute worm and the counterpart rack, as well as the counterpart rack and the helical gear are presented, and the computational model of contact ratio and contact ellipse are obtained through the counterpart rack. The mathematic model for the instantaneous contact point and contacts trace of the worm drive with different assembly errors is established, and the meshing performances are investigated through the numerical analysis, simulation analysis and performance testing. The results show that this worm drive is insensitively to the assembly errors, and it is beneficial for reducing the vibration-noise and extending the service life. This theoretical research provides theoretical support for further optimizing the vibration and noise of involute worm and helical gear drive and improving the fatigue life.