SYNTHESIS OF GEAR AND CHAIN DRIVE WITH EVOLUTE PROFILE AND HIS MODELING IN THE CAD-SYSTEMS

Abstract

The article considers by synthesis of evolute mesh for gear and chain drive and his modeling in the CAD-systems. The Bobillier construction which is to replace the gear mechanism equivalent to hinge-lever mechanism. Based on it is proposed a method for finding the working tooth profile of gear or chain drive sprocket. The advantage of this method is smiling in-ability to manage quality indicators of chain mesh on a stage for the synthesis. Differential equations that describes the basic rack profile for gear or sprocket tooth profile for chain drive were obtained. The solution of the synthesis by integration of the differential equation was obtained: a) as a polynomial approximation using Vissim software; b) numerically by the Runge-Kutta method in the MathCAD system. Examples of synthesized profiles for evolute gear pair and sprocket are given. The resulting arrays of the profiles points coordinates were exported through an Excel file to the Autodesk Inventor system for build 3D-models of gears and sprockets. In order to ensure a smooth change of the tooth profile curvature in the 3D model, the calculations accuracy in MathCAD is set by force – 7 decimal places. A technique for constructing solid and finite-element models of gears and sprockets in Autodesk Inventor has been developed. The pinion and gear sectors were adopted as the calculation model of the gear pair, the sprocket sector and one chain hub were used for the chain drive model. In both cases, the sector consists of five teeth and a rim with a recommended thickness of 3 modules. Used half width gears and sprockets. The research results allow to create new gears and chain drivess with improved characteristics and perform their modeling in modern CAD-systems.

Key words: evolute mesh, gear, chain drive, tooth, sprocket, Bobillier construction, synthesis, CAD-system, Autodesk Inventor.