Design And Simulation Of The Elimination Backlash Mechanism Of The Gear Transmission For NC Machine Tool

For a large and heavy NC machine tool with a travel more than6~10meters,pinion and rack drive are often used in servo feed execution unit instead of ball screwdrive, to improve the stiffness of transmission and support, achieve large stroke (racksection splicing) and lower the cost, etc. However, the transmission accuracy of gearand rack should be improved for high-precision NC machine tools. In particular, thereverse feed transmission clearance should be reduced or eliminated, to improve thecoordinate positioning accuracy and the repeat precision. Therefore, the methods toeliminate reverse clearance were studied, and a double-gear anti-backlash was designedand simulated.Firstly, the impact factors of tooth gap width and its influence on the transmissionaccuracy were analyzed, a method to eliminate the gear backlash was proposed. Thepresence of backlash will cause return difference, nonlinear transmission and oscillationof the system, which can seriously impact on the accuracy of NC machine tools. Themethods to eliminate gear pair clearance and their characteristics were analyzed. Then, adouble-gear output transmission backlash was proposed to eliminate the gear racktransmission clearance.Secondly, the double-gear anti-backlash mechanisms were designed and discussed.By comparison, the spring anti-backlash mechanism was finally adopted under theprinciple of simple, compact, easy to control, convenient in operation and maintenance,and lower cost. The general design and optimization methods were also studied. It isdemonstrated that the volume of gear box decreases10%~20%by using Matlabsoftware to optimize the gear and transmission parameters.Finally, the3D model of the double-gear anti-backlash mechanism was constructedand assembled by UG software. The motion simulation was also conducted by ADAMSto analyze the anti-backlash effect of this mechanism, based on the relevant motion data.It is verified that using double-gear anti-backlash mechanism can eliminate the returndifference caused by gear rack transmission clearance. In consequence, the studyprovides theoretical and practical references for anti-backlash mechanism design, andthe designed gear anti-backlash box can directly applied to practical production...