Kesici takım asimetrik diş ucu yarıçapının diş dibi eğilme gerilmesine etkileri

Abstract

Proposal of a new asymmetric tip radius of symmetric cutter • Reduction of tooth root bending stressesPurpose: In scope of this study, the effect of symmetric and asymmetric tip radii of cutter on root stress is examined by keeping all other gear parameters constant. Theory and Methods:For gears modeled by FEM in this study, first, symmetric (the same) tip radii coefficient of cutter for both drive and coast sides (as given in literature) are used, then asymmetric (different) tip radii coefficients of cutter for two sides of gear tooth profile are used to benefit from larger radii of curvature to reduce the bending stress on drive or tensile side of the flank. Results:When applying "asymmetric cutter tip radius coefficients" of 0.58 and 0.36 (for drive and coast sides, respectively), a stress reduction of nearly 10 % is obtained, with reference to symmetric condition of 0.38 / 0.38 coefficients as suggested in international standards. Based on FEM stress analysis, increasing symmetric cutter tip radii coefficient beyond 0.38, up to 0.47, helps decrease root stress an additional 6.5 %. This is an extra potential for stronger gears carrying more torque/load. Conclusion:Considering the small design change made to cutter geometry, the benefit of 10 % reduction in bending stress is a considerable benefit resulting in either a longer service life under the same torque transmitted or an increased load/torque capacity with the same service life. Such fillet-modified gears, manufactured based on generation method, such as in conventional hob and rack type cutters, are also expected to be less expensive than gears with non-trochoid specific/special fillets.