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

Abstract

The article considers to the problem solution by increasing the wear resistance of the sprockets tooth profiles for bushing-roller chain drives and for driving wheels of the tracked mover. A mathematical model of the wear process for the sprocket tooth profile has been developed. First, the coordinates of the points of the tooth profile are calculated. For standard drives, the profile is calculated using generally accepted methods. In the case of an evolute mesh, these coordinates are the result of a numerical solution for a second-order ordinary differential equation (ODE). This equation describes the profile of an evolute tooth. A profile is built in the x, y coordinate system. The center of the system coincides with the rotation center of the sprocket, and the y axis coincides with the tooth axis of symmetry. The profile is then approximated using third-order Bezier curves. Further, at the calculated points of the sprocket tooth profile, determinate the relative sliding speeds, curvature radii of the profile, contact stresses according to the Hertz formula for the initial tangency of elastic bodies along the line. After that, at these points, the values of the tooth profile wear are calculated for one load cycle. The coordinates of the points for the worn profile are determined. Next, new values of sliding velocities, curvature radii and contact stresses are calculated. After that, the value of wear on this cycle, new coordinates of points for the worn profile, etc. are calculated. Simultaneously, on each cycle, the total wear of the sprocket profile at each point is calculated and the maximum wear value is found. Thus, we have an iterative process that stops when the critical wear value is reached. And at the end, the resource of the chain drive or tracked mover is determined by the criterion of limiting wear of the sprocket profile. The created mathematical model is quite versatile – it can be used to study bushing chain drives and a tracked mover with any standard or non-standard sprocket tooth profile. Its use in the design process will make it possible to create chain drives and tracked movers with increased wear resistance.

Key words: chain drive, mathematical model, sprocket, tooth, wear.