A miniature non-circular line gear with pure-rolling contact

Abstract

The design of pure-rolling gear has always been a subject of intense research, because in some working conditions, such as dry friction, pure-rolling gear has higher transmission efficiency and less possibility of transmission failure. Non-circular gears have played an important role in mechanical devices and robots. To date, there is no effective method to design a pure-rolling non-circular gear with relatively small number of teeth. Based on the space curve meshing theory, a pure-rolling non-circular Line Gear (PNLG) mechanism was presented in this paper. Firstly, the fundamental design method of the PNLG was proposed, which included the derivation of the contact curves, the obtainment of the teeth number and the solution of the rotating angle function. And, the rotating angle function was selected as a segmental quartic curve to ensure the dynamic stability in the meshing process. Afterwards, a pair of PNLG was designed for finite element analysis (FEA) and kinematics experiment. Finally, prototypes of PNLG pair were manufactured by using of 3D printing, and transmission ratios were measured on the test rig. The simulation results and experimental results indicate that the devised PNLG is feasible, that is, the PNLG can smoothly output the preset rotating angle and angular velocity. The designed PNLG mechanism might be used in some special cases, such as the occasion without lubrication and miniature devices.

Keywords

• line gear
• contact curves
• pure-rolling contact
• non-circular gear
• miniature gear