Fundamental analysis of linear type trochoid gear (1st report) - Motion principle of trochoid cam rack

Abstract

It is important to eliminate the backlash and to reduce inertia for high accuracy linear motion system. For this reason, the trochoid cam rack has been developed. The profile undercut must be avoided to satisfy the required performance. So this rack profile is ground using trochoid curve loci. In this report, the motion principle has been analyzed, and it becomes clear that there is the optimal value of rack profile offset factor which affects on pressure angle and radius of curvature. Also, roller diameter and tooth height affects on those characteristics. The optimal cam rack without profile undercut is designed using the selected each design factor. The prototype cam rack system using optimal design value is made and tested. It is proved that the system has high positioning accuracy without backlash.